Shirts are a double edge sward kind of thing. You kind of need to order a ton of shirts to make the price low enough that you can sell them at a price fans want to pay and make a profit... but they you have so many shirts you will never sell them all, or the investment cost is too high. On the other hand if you order a small batch, they cost way more, and then you have to sell them for so much to make money that nobody wants to buy a shirt that expensive.
My band has had pretty good luck buying the shirts ourselves and finding local dudes to screen print them. Have done this twice already, and about to design a third shirt!! We sell em for $15 bucks - which people seem to be OK with. For a longsleeve, it's $20. Sometimes we will let them go for $10 depending on the situation.
Our last batch I ordered about 50 blank shirts - good quality Hanes, long sleve, short sleve, and in a bunch of colors. We got a local buddy of ours to screen em (he owed me a favor), and we have about 25 left that we are going to come up with a new design for...
Our first order we got really cheep shirts - you just order the size and color, and they send you a mix of brands that are "B-stock." Not irregular, but just didn't make the A-list for what ever reason. Our second order, we specifically got a name brand shirt and paid more. I though people would go for the better shirts, but more people go for the mixed ones because of the cool design... so I say design trumps shirt quality... unless you get really expensive shirts - American Apparel - in which case advertize them as such, and people will buy them for the brand name... like my girlfriend who bought an American Apparel concert shirt from a band she doesn't even like because she likes the shirts.
When it comes to regular T-shirts, I think a good design is most important. And SIZES!!! I turn away a lot of sales because we don't have your size. That sucks. I got more mediums - thinking most people are medium... a lot of dudes want to buy shirts, and they wear L and XL.
