Have a look on eBay - I've had a dug around and there are plenty of currency bundles from Germany, Zimbabwe, and Venezuela.

Ironically though, given that everyone is trying to collect this stuff now, the prices of high notes can get quite absurd. E.g. I've seen $100 trillion notes being listed at more than $100 USD apiece and that seems to be the going market rate.

Definitely not a great buy imo. Just accept a slightly lower denomination (still in the billions/millions) and move on.