i dont think setting up a store would be a problem if you dont have "time" to do the orders, shipping and stuff... i mean they have online services like
http://www.zazzle.com where you just submit your design and post them up for sale and the rest of shipping/payments/customer services will be provide by their team... and i'm sure there are other competitors other than Zazzle out there... like Yahoo also have something like that i believe. just my 2cents.