Don't remember hearing "crooked as a two-dollar bill"; but "crooked as", or "phoney as", a three dollar bill was actually a pretty common idiom around home.

A variation on that was referring to someone of suspect sexual orientation as a "three dollar bill".

One thing that hasn't been mentioned is "ten spot", commonly as in "can you loan me a ten spot"; I may have heard "five spot" sometime, but I'm pretty sure I never heard any other bills referred to that way.