We use Boombah, not sure what your budget is. The nice thing is that once you get your logo set up with them it's easy to re-order or order additional stuff.
Depending on how much you have to spend, here are a couple of companies I have worked with successfully in the past: Pro Look Sports does custom everything for a set uniform price. Boathouse Sports is a great co. to work with, too. They specialize in jackets, and lacrosse, but have a great softball line where you can customize your uniform elements. Most cities have 2 or 3 local screenprint/embroidery shops that will screen or tackle twill whatever you want. PM me if you want contact info for the local company I work with when I'm on a tighter budget. They'll ship anywhere. I don't want to look like a shill, though.