Folding gatorskins can be found at pbk for less than $30 with free shipping to the US. Also get another 10% off with USA10 coupon code. The downside is I've heard reports of orders taking a long time to arrive (customs/shipping) so if you need tires for the weekend you'll want to go elsewhere.

I'm trying not to order the GP 4000 S for $34. If you don't have to worry about a lot of glass and debris where you ride, the GP 4000 is pretty decent. I have a set and am looking at getting a spare set now in case the pound comes back against the dollar.