Yes, they are so expensive because 1) there is printing on the front and back and 2) it is printed on a dark t-shirt.
I did create a t-shirt that was only 1-sided:
Ngemu - just front T-shirt from Zazzle.com
Also, I noticed that Zazzle is having a $5 off coupon code right now: ZAZZLE5SHIRT
So you could get a 1-sided shirt today for $16.95 + shipping.