You can spend as much or as little as you want on custom screen printing. If you need 100 T-shirts for giveaways at an event this weekend, and you need to get them for $4 each, that's no problem. Go with white T-shirts, and a 1-color front print and you're in business.
In general, in screen printing, there are two rules:
1. Color Costs Money
We make a screen for every color in a T-shirt design. And for every added screen, there is labor involved in creating the stencil, calibrating the press so that the added colors line up with one another, inking the screens producing test prints, and tearing down the job when finished and cleaning the screens for storage. Generally, you can get great value with 1-, 2- and 3-color prints, even at smaller quantities. But if you want highly-detailed, multi-color images, then small runs of a couple dozen T-shirts can get costly.
2. Quantity Saves Money
After we've spent anywhere from an hour to an entire day preparing the press with your image, we can produce prints very quickly. Therefore, we offer enormous quantity discounts. The shirt that cost you $15 each when you ordered one dozen might only cost you $8.50 if you order 48 of them. We pass the savings of the increased efficiency on to our customers. In fact, keep this quiet: We've printed high-quality, name-brand T-shirts for less than $4 each for some very large production runs. Most of the cost of printing is in the labor to make the first item come out just right. After that, the economy of scale kicks in very effectively.