I used a local place when I first started doing shirts but got sick of having to pony up $500+ to sit on shirts for a while. I started using Cafe Press and Zazzle. I don't want to take away from the shirt shops but this has made more pocket change for me and I don't have to stock any. I've sold shirts around the globe this way. You can make a decent store online too. I designed all my shirts using Corel Draw then uploaded the imaging. I enjoy that kind of stuff, though. I've ordered my own shirts from there as well so I can be a walking billboard for my box. Here's my Zazzle site.
http://www.zazzle.com/crossfitoftheozarks (wfs). For what it's worth.