I'm currently prototyping a Monopoly style game and was in need of game money, as I had already canabalised on my all old board games. The game material online shops I found, didn't have game money or they had 1 specific sort that didn't fit in currency and denominations.
I then found www.mygamemoney.com and I have just completed my first order for custom made game money for my game. You get to choose denominations, currency, bill color, fonts, custom central picture, background, etc. There is even a lot of extra options for instance special paper. You can buy as little as 1 set (240 bills). You can get the bill images sent by email as pdf if you would rather print and slice yourself.
Well I'm impressed - and it's not even expensive.