I really like my simple and cheap Nashbar Townies - I have some other nicer pans for commuting and the like - but nothing beats the townies for shopping. They have a rain-resistant cover that zips inside, they fold up when not in use.

I bougth mine after reading this review
http://www.kk.org/cooltools/archives/000674.php

I note they've cone up $3 in price.