I am currently making a browser-based game and I would like to integrate micro-transactions. However I would prefer not to have to implement my own storefront. Does anyone know of an available framework/API? I've been looking at commonly used ones and most of them seem to be in-house work, i.e. EA's FTP games use http://www.play4free.com/en/ I'm looking for something like this but available to third parties.
Thanks in advance.