Are you looking for places that make shirts for you, or other band's merch?

There are plenty of retailers that will make shirts for you if you submit a design for them to put on the shirts. Otherwise, you have outline what you want to a graphic designer, who will conceive drafts and proposals for you to evaluate. If you are looking for band t-shirts, band's myspace and websites usually have direct purchase options, and they usually have an online shop.

IncuEdit: Never mind, I just re-read your post, for starters, you probably are looking at about 300 shirts for your first shows, so that if you are doing several, you can have enough. Get quotes from retailers first. If you live in Sydney, Australia, I can give you the websites of some merch distributors and t-shirt printers.
Quote by dannyniceboy
I consider myself to be really intelligent and I've gotten into a fight coz this kid thought it was nasty to put sour cream on enchiladas.

Quote by Minkaro
The fact that I went TOO high singing a Darkness song on Singstar

as far as how many, dont get too many unless they start to sell out. just get someone to sell them at your shows, add a way to buy on myspace, etc. until it becomes apparent that many people are buying.

Saying the Red Hot Chili Peppers have no talent is like saying Guy Fawkes didn't have an epic mustache.