gifts

I am working on a gift giving site. I wanted to use user points to negotiate the transfer of user points from one member to another member.
Eg.
Bill wants a pony. (worth 500 points).
Jenny wants Bill to have a pony (click on a button and Bill get 5 points towards his pony deducted from Jenny's balance).

Is there a module or a recipe that exists that allows this to happen? I know how to build something like this and tie it into the Userpoints API, but I would rather not re-invent the wheel, if I could.

Thanks in advance!