i use a free service and the cheaper shirts don't match the quality of shirt i would want my fans to wear (or myself even).
i use printfection that doesn't charge me to have my store
but they have a set price for their shirts then you add how much
commission you want from the shirt (which raises the price of the shirt).

the wacker shirts start at like 17 beans
so even throwing 2 dollars commision on it is over priced for the quality given
so i decided to use their american apparel line (the colors are limited
but the quality of shirt is 100 times better)

now if you go to a service like jakprints.com its gonna cost the
artist even more but again the quality of the shirt goes up to wear
someone would actually rock the shit more than 4 times before it
starts fading (which was the case with the first set of t's i was
pushing).

quality costs. the thing about that is now you have to take that
quality and make it so the person who loves your music sees that tshirt
and they MUST have it.

or even package it with your music. there are ways.
but yea GOOD tshirts just ain't cheap.