It just seems to me that outsourcing a huge pain in the ass. Do I have the rights to the source file? Does the graphic designer have the rights to the images or fonts they are using? In the end, I've just decided that I'm going to make my own designs. I suck at it but they do sell. I know that I've bought my images and fonts as well. I won't be able to mass scale but I feel like I'm cutting down on the risk of losing my Merch account.
The whole business practice in graphic design can be overwhelming to how much to charge and who owns the rights. Keep at it. You will become better in design the more you do it.