If you don't mind waiting, you can get some really good deals out of China/Thailand on eBay.
Every now and then, you'll get a good deal from the States on there as well... I just got 100 24pin sockets for under $10 shipped.
You just have to keep an eye out and compare the prices.
If you're in a hurry though Jameco, Digikey, and Mouser offer pretty good bulk deals as well.