If you make it a no-maintenance sort of thing, it won't be a real burden. There are places that will print stuff like T-shirts and tote bags and the like on demand, so you just have to post the stuff and let people buy it. There's a few options out there. I don't know much about any of them though. Looks like you can learn more through these sites:
http://mashable.com/2009/09/05/sell-products-online/
http://www.selltees.com/