Start asking around. There are plenty of basket cases around. Guys tear down their bike in hopes of building a custom, they have a kid, the bike gets put on the back burner, and never finished.... You get the idea.
A buddy scored 2 Sportster frames, 3 motors, and a shit load of body work for about $1000. You just have to find it. Sorry, i dont know of any basket cases.
Just make sure the bike isnt stolen before you buy it...