This has hovered around the $45-50 mark delivered from the usual places -
Manufacturers website here - https://inkbird.com/products/bluetooth-pool-thermometer-ibs-…
And, it's supported by Home Assistant!
https://www.home-assistant.io/integrations/inkbird/
Floats in ya pool and tells yer the temperatures!
I had one of these and found that it went through a pair of AAA batteries every 4-6 days, rechargeable which seem to have a lower voltage than disposables would be lucky to last a day :(