Haven't you ever made shirts before?
Please, show me where you can order 20 shirts for $10 each. If you want to make a decent looking shirt that is good quality (a shirt without just plain text ironed on), it will cost more than $10 per shirt, and you will need to buy more than just 20 to get a good deal with it. Added with shipping, it's not even worth buying.
Like I said before, someone needs to put in start up money. I don't think Sythe would be willing to invest in this, because it probably won't bring in money, so if you really want this to happen then you will have to put in a few hundred dollars.