Definitely possible, but you would likely have to combine RunUO coding with some sort of web based shopping cart thingy that could accept payment and send delivery information to the RunUO server. IMO the main concern with a system such as this would be ensuring the payment information was kept secure, and that there were no errors/exploits in the system that could cause incorrect payment processing. Playing with money on the net can be scary business if you aren't careful/don't know what you're doing.
I haven't seen any scripts like this on the release forums myself, but that does not mean they don't exist.
*edit: I searched the custom script releases forum for "donation system", and this was the first one:
http://www.runuo.com/community/threads/runuo-2-0-fully-automated-donation-store-system.98542/
So people have made these before, but like I said, dealing with money online can be scary, so use anything at your own risk, and your mileage may vary!
