@qdot Managing tshirt size inventory is a huge pain: you'll always have too few of some sizes and way too many other others. If you're not looking to make money, print-on-demand is so much easier to deal with, though quality is usually mediocre. (I don't have POD recommendations, though)
Sticker-wise, I love Stickermule's quality, color reproduction, and response time. There are probably cheaper options out there, but their service is A+.
A small server for a small group of dog things