Whether you need paper goods or T-shirts & more I highly recommend these 3 online services. I have used all 3 personally and they are fast to complete and ship every order! I haven’t been disappointed yet!
It’s free to create an account and upload designs/photos etc, just pay for products!
I have a cafepress store and will happily customize anything you need there!
I intend to set up as a vistaprint reseller when I start getting customers who need that stuff!
I’ve also tried zazzle.com – they’re ok for quick items but a little confusing with the interface and store set up.
They cover T-shirts and the like, though they also have postcards & cards as well.