Here's the old uncomfortable one for $21 new.
Garmin Heart Rate Monitor
https://www.amazon.com/dp/B000UOD5QM..._sRz3CbHMK136P
Soft strap for $49.
Garmin Premium Heart Rate Monitor (Soft Strap)
https://www.amazon.com/dp/B00BI9X1QM..._8Rz3Cb4QNP2SC
And a no name ANT+ one for $30.
CooSpo Fitness Tracker Ant+ Heart Rate Monitor Chest Strap IP67 Waterproof with Bluetooth for Wahoo Strava Zwift …
https://www.amazon.com/dp/B07BS6B4PD..._uTz3Cb9VHPA76