We wish we could print "just one" for every shirt style we offer, but sometimes shirts must have a minimum order of 6.
First, to print just one of any item, it must be MOSTLY cotton, so must be between 80/20 cotton/poly, up to 100% cotton. If there's too much polyester (or other fabrics) the ink doesn't stick to the shirt and it will fade and wash out.
Second, some items aren't stocked nearby our warehouse in Tempe, Arizona. If you order just one shirt and it has to come from a warehouse a few states away, and you are the only customer ordering that particular item at that time, the cost of the shirt would go up substantially as we ship it to our warehouse to print. We would prefer to keep the cost down for you, and only offer shirts that do not require extra transit. We can sometimes make exceptions, so if there is a shirt you truly must have and only need one, just contact us and we can give you a special quote.