We get this question, "what should I look for?" a lot, and while I understand (and sympathize) with the intention behind it, I think it's the wrong question. I mean, okay... let's just say a Claud Butler Olympic Sprint frame is exactly what you're looking for. But if you limit yourself to that specific model, you will make it almost impossible to find one. I think you should just look at what's available, and remember your standards: it has to be your size, no funky threading, no lead pipe, whatever. And you'll do fine. Especially if you don't care exactly what it is. You might find a frame on ebay that's been repainted and its identity lost, which invariably reduces interest and therefore reduces the price. But if it suits your needs, there you go.

I found one like that a few years ago... just what I wanted, but no one knew what it was. Came pretty cheap. Took me a couple yeas to figure it out: it was a Claud Butler Olympic Sprint.