Used Road Bike Frame?

Does anyone have any suggestions where I can get a deal on a used road bike frame (56 inch)? I was in Bloomington, IN riding this weekend and my frame broke while I was climbing a monster hill. I've been riding a specialized Allez Comp for about 10 years and would like to try something different.

I'd like to get a CAAD9 or something similar. If anyone has any suggestions on where I might look to get a really nice frame that is a year or two old toss them this way.

Casey