On-demand Prints and Merchandise
The two main companies I currently use for on-demands prints are Society 6 and Inprnt. They both have excellent reviews from other artists. They both do gallery quality prints (aka. glicées or archival prints). I can vouch you are buying a good product. A high quality print is a great alternative to buying the real-deal original artwork and can actually acquire value in itself if it is properly taken care of over the years.
Not sure if buying art is a good choice? Read here.
Society6 Prints & Merch