Alot of the custom jobs done lately are done for rich (unts who are just after a show quality bike. have more $$ than sense.. if you have the know how its not that hard to make a jig and weld up your own frame.. from there you can get forks either made or imported, a nice set of billet wheels, a nice wide 300 rear end, the lists endless obviously..
To do things on the cheap look at some of the older choppers.. Triumph's are commonly converted to choppers, not as wild as the yanks do them but non the less cool and classical..even old honda 450's?? are common.. keep an eye in jsut bikes for some.. they are often advertised around the 5-6k mark.. but will need a good clean up..