How can a decorator determine which sublimation printer to buy?

Buy one that is warrantied and supported for sublimation printing (ask about an extended warranty, too). Make sure an ICC profile is provided and that your sublimation partner assists with installation and future support. Be aware that the cost of printing may vary based on the size of the ink cartridge(s) being used (some printers utilize standard-size cartridges while others offer extended-size cartridges that reduce the cost of ink). Keep in mind that the size of the printer determines the size of the substrates you can produce; a larger print size allows you to produce a larger variety of products.