Leaking thermostat housing, best gasket???

I wonder if any one has found a good gasket that is less prone to leaking for these darn thermostat housings? Mine is bran new and leaks. It is driving me nuts! And I have a hard time swallowing the $100 price for the new "guaranteed not to leak" O ring housing. I am sure he has a lot of work in them, but dam $100 for that little thing. Thanks for any help!