I bought a top and bottom from Hodgman years ago and still use them. These aren't the same ones, but at less than $12.00 each you don't have a lot of downside risk:

http://www.hodgman.com/Fleece-UnderW...-P2032C46.aspx

http://www.hodgman.com/Fleece-UnderW...-P2033C46.aspx