Tim--I think you can actually get tags pretty cheaply, and without requiring a huge order. My mother-in-law bought a pack of 50 or so with my wife's name on them to put on knitted projects my wife completes, and I think they were fairly cheap.
I wouldn't get too wrapped up in branding, marketing, website design, etc., at this point. The quality of your work speaks for itself (and speaks loudly, in these forums!), so at this point the best marketing strategy is probably to continue doing good work. Your name is out there, people see what you're doing, and it sounds like you have about as many orders as you can keep up with, unless you decide to go to the next level and make this your full-time job.