Wow, now I feel pretty stupid going with a local company at $20/shirt!
What I found in my research is that most franchised stores are more expensive--they have minimums to worry about and their franchise fees.
I went local, and yeah, $20 ea was the best I found around here. Everyone else wanted $30-$50 each!
I found someone who used digital printing, as we're a painting company so let's face it: the shirts are going to get abused. Digital printing is much, much cheaper than silkscreen! Or embroidering. Find a local digital printer with no minimums (I bought 6 shirts).