A 4-wire loop-powered Pt100/RTD head-mount transmitter with HART, ±0.1% FS accuracy, and 1.5 kV isolation lists in the US$30-220 per-piece band on Chinese sourcing platforms as of 2026-08-13, while bare sensor-only modules sit at US$1.50-3.50 per piece at 100-piece MOQ [S6].
The spread is driven by what sits on the same PCB, not by the Pt100 element itself: protocol stack (analog 4-20 mA vs HART vs IO-Link vs Bluetooth/WirelessHART), galvanic isolation rating, accuracy class, and hazardous-area approval each move the unit price by meaningful multiples.
Cost driver breakdown: what actually moves the price
Four cost levers dominate every temperature transmitter quote. (1) Sensor input class: TC type J/K/T/E millivolt inputs with upscale break protection, as in the OMEGA TX93A/TX94A ultra-miniature series, fall in the entry band, while 4-wire Pt100 with matched IEC 60751 curves adds roughly 20-40% [S5]. (2) Output protocol: pure 4-20 mA analog loop-powered heads are the cheapest layer; HART 7 overlays typically double the electronics BOM; IO-Link point-to-point (as in the ifm TA2/TA1 Pt1000 series) targets cabinet-level installation rather than field head-mount and prices accordingly [S1]. (3) Isolation: 1.5 kV galvanic isolation, explicitly called out in the Masibus TT7S10/TT7S11 spec sheet, is a real line item because it forces a DC-DC on the PCB plus through-hole creepage/clearance [S3]. (4) Wireless radios: the YZ9405 2.4 GHz Bluetooth wireless transmitter adds a lithium-battery subsystem and a radio module, putting it into a separate cost tier entirely [S4].
For a 4-wire Pt100 HART head-mount with 1.5 kV isolation, expect the analog baseline to roughly double once HART is added, and to roughly double again once you move from non-Ex to Ex d or Ex ia certified housings. None of the public listings in this date window expose a single OEM's Ex-certified price, which is itself a signal: hazardous-area units are almost always quoted through regional distributors rather than listed on open catalogs [S2].
Price-tier comparison across the main options
The 2026-08-13 sourcing landscape splits cleanly into four tiers. (a) Entry-level sensor modules, US$1.50-3.50 per piece at 100-piece MOQ, focused on Focus Sensing and Control Technology-style PCB-only Pt1000 modules for OEM integration, with no display and no protocol beyond raw resistance or mV [S6]. (b) Standard industrial head-mount 4-20 mA, US$30-220 per piece at 2-piece MOQ, programmable for Pt-100, thermocouple, mV, and resistance/potentiometer, exemplified by Masibus TT7S10 (2-wire loop), TT7S11 (4-wire auxiliary), and TT7S10-H (head mount) with 1.5 kV isolation [S3][S6]. (c) Premium smart and IO-Link units, list price on request, including ifm TA2/TA1 Pt1000 with IO-Link and hygienic variants in 25-150 mm installation lengths, plus OMEGA TX93A/TX94A ultra-miniature (35.6 mm / 1.4" diameter, ±0.1% FS, 4-20 mA only) [S1][S5]. (d) Wireless and specialty, list price on request, including 2.4 GHz Bluetooth units (YZ9405) and explosion-proof MP/HP wireless pressure variants used in tank and pipeline monitoring at -40 to 125 °C [S2][S4].
Across these tiers the dominant specification shifts are: enclosure diameter drops from DIN B-head (roughly 44 mm) at tier (b) to 35.6 mm at tier (c) for space-constrained retrofits; accuracy class tightens from typical ±0.2% FS at the entry tiers to ±0.1% FS on premium ultra-miniature heads; and output count rises from a single analog loop to dual-channel differential transmitters (NOVUS TxIsoBlock-HRT, Yunyi PT100 differential probe) that share a single HART address [S2]. Differential and dual-input types are listed in low volume, 4 products across 3 manufacturers on DirectIndustry, and command a price premium because of the HART stack and matched-pair sensor calibration [S2].
Selection criteria: which tier fits which job
Pick the tier by three questions, in order. First, is the transmitter mounted in a field head (DIN B thermowell) or in a cabinet on a DIN rail? Field head-mount needs an enclosure rated for the process environment (IP66/68/69K for washdown, as in the ifm TM/TT series) and a head-mount form factor; cabinet-mount lets you pick an IO-Link device like the TA2/TA1 and wire Pt1000 back to it [S1]. Second, do you need remote configuration from a handheld or asset management system, or is a fixed analog loop enough? If yes, HART (TxIsoBlock-HRT, DPT-2000) is the default; if you already run an IO-Link master in a modular PLC, IO-Link is the cheaper, faster commissioning path [S2]. Third, does the process side require hazardous-area certification? ATEX/IECEx adds a real cost step and pushes the lead time into distributor territory [S1][S2].
For a typical 4-wire Pt100 retrofit in a non-Ex utility service, the cost-effective spec is a 2-wire loop-powered head-mount with 1.5 kV isolation and HART, programmable for Pt-100/TC/mV/resistance; that profile matches the Masibus TT7S family and the Nanjing Hangjia unit priced at US$30-220 per piece [S3][S6]. For a hygienic food/pharma line, step up to a Pt1000 with IO-Link and an IP69K probe, as in the ifm TM4/TT clamp-on hygienic family, accepting that the price moves off the open catalog [S1].
Total cost of ownership beyond the unit price
Unit price understates the bill on most real installs. Installation costs include thermowell machining (stainless 316L for CIP/SIP, as in ifm E35 series screw-in thermowells), head wiring (2-wire saves on conduit, 4-wire saves on loop-error budget but adds a pair), and any surge/transient protection on the field side [S1]. Calibration cost is a hidden multiplier: a 4-wire Pt100 with matched IEC 60751 curves plus HART lets you trim in situ over the digital link, while a 2-wire loop with no comms forces a bench calibration or a hot-cal swap. Battery-powered wireless units (YZ9405) shift cost from cabling to a lithium-battery replacement cycle, so the TCO math is years of battery life versus the copper cost of running a new analog loop [S4].
For high-availability processes, the third cost driver is mean time between recalibration, where the ±0.1% FS ultra-miniature class (TX93A/TX94A) buys longer intervals than the typical ±0.2% FS tier; the price premium pays back in fewer proof-tests, but only if the loop has the digital read-back to use it [S5]. Across the comparison, a tank-temperature loop in a chemical or petrochemical reactor is the canonical use case for a HART differential unit (DPT-2000, -200 to 550 °C), and it is the application where isolation, HART, and dual-input capability all justify the tier (c) spend [S2].
Constraints, failure modes, and sourcing reality
The published landscape has three honest limits. First, open-catalog prices (US$1.50-220 per piece) apply to non-Ex analog/HART units in small MOQ; HART, IO-Link, wireless, and any hazardous-area certification sit behind "Contact manufacturer" or distributor quote flows, so a US$30 list price is not a like-for-like against a US$300 quoted smart head [S1][S2][S3]. Second, the ultra-miniature 35.6 mm class (TX93A/TX94A) is marked discontinued by the manufacturer with an explicit upgrade to the TXUN series, so any quote on the legacy part is end-of-life and should be sanity-checked against the replacement [S5]. Third, for 2-wire loop-powered heads, the supply voltage budget (typically 12-36 V DC across the loop) constrains where you can place a 250-ohm HART resistor without losing headroom for the transmitter itself; that is an installation constraint, not a price line, but it is the most common reason a "cheap" head-mount has to be swapped for a higher-tier 4-wire version.
Trackable next signals: the ifm TA2/TA1 IO-Link hygienic Pt1000 family will be shown at Intermat 2027 (21-24 Apr 2027, Paris) per the supplier's own listing [S1]; the OMEGA TX93A/TX94A EOL is already on the manufacturer page and pushes buyers to the TXUN replacement [S5]; and the differential temperature transmitter category on DirectIndustry remains thin (3 manufacturers, 4 products as of 2026-05-23), which is a useful demand signal if you are sourcing a matched-pair HART unit [S2]. Related selection work for differential pressure, level, and temperature transmitter reference pages is also worth bookmarking for cross-loop specification. For sourcing tactics, see also this loop-by-loop selection walk-through on process temperature versus level and displacement and a spec-first view on pressure transmitter selection in compressed-air service.