Welcome to our forum.
I'm thinking of buying this one:http://www2.oregonscientific.com/shop/product.asp?cid=4&scid=68&pid=616Seems that you can use it "alone" or connect it to a weatherstation. Maybe a little expensive but it would be nice to check temp in the spa without going outside/lifting the lid//Thomas
MattNY, sorry for maybe the dumb question, but do you get the "exact" temp from the spa? If it supports celcius (I'm in Europe), it's sound like a better deal