Will you accept DerpCoins? It's a cryptocurrency that I totally just made up; but it definitely has real value because I say it does, and I know plenty of people who use them.
How about Potats, I know those have a fairly stable value in the fake marketplace.
If all else fails, I guess I can always pay you in rocks; I know there are some people who accept that as a currency somewhere.
No but seriously, stop selling stuff on the forums, especially for fake currencies. I think this could even be considered scamming to some.