Most bill changes use normal examinable (usually borrowed) banknotes. So long as they can be folded up into a small packet, they can be used for a bill change.
It's the fact that a bill is borrowed that makes the effect interesting - although I'd recommend turning a spectator's £20 into a Scottish £1 note rather than upgrading it to a fifty as many performers do. Downgrading their money gives them a vested interest in seeing the routine to its conclusion, and not just saying, 'thanks very much', and snatching the new note from you.
It's been known to happen.
As for source material...
SWITCH by Daniel Lovick is regarded by many as the best dedicated tome on the subject.
Michael Amar has workings on the bill change in
The Magic of Michael Amar.
Sankey has a DVD on the subject -
Hundred Dollar Miracles
There's a variation available from
Top Secret Magic,called
1-100 and doesn't use the usual secret something - just two banknotes. Look under Close-up Magic)
And I also found
this available cheap online, whichj I believe to be the basic working.
Hope that helps.
Pete