Itemshop?
 

Is there anybody who has made an itemshop to add on to a site? I think I've heard about it (and also a battle system) but I'm not sure how to find them. Please help?

Well itemshop feature is under development for Mys v1.3.0 major release, which is projected to be released in summer. A public battle system, however, is not likely to emerge in the year 2011. You can always hire a coder to make a custom battle system that suits your need though, but it will be quite costly.

Depending on how popular your site is either start a donation drive for such features or use ads. To fund for a coder.