Where to get a frame

Hey guys,
Well, at the moment, I'm saving for a mountain AND a road bike (took my old bike for a ride last week and became obsessed with bikes again!). Now I'm interested in a SS bike, too. I'd like to build my own though, so I can add my own flavor to it. I'm pretty good at building bikes, as I used to ride BMX years ago and I was my own mechanic. So my question is, where do you guys look for frames? I've been asking friends/family if they have any junk bikes around, who knows what they might have, but nothing yet. I'm going to a "farmers market" on Sunday and I know they have alot of bikes and frames. Is there anything specific I should be looking for to build a SS? Any tips would be appreciated. Thanks!