Hey all, I work for GameSparks (important to point that out so forgive me if this is self-promotional) ... GameSparks is a middleware platform that integrates with many of the main payment systems (including stores) and provides a full virtual currency management solution for a game. Its all pretty easy to set up. You can see more on www.gamesparks.com or you can register for free here: https://portal.gamesparks.net

There is documentation explaining how to manage currencies in the support area.

What do you think about this guys? http://pspcore.ismachine.net/im/sandbox.jsf

I touched them. As I understand they concentrated in payment business, but could give me what I am looking for very cheap citing it with simplness of setup process.

Thanks!