[monkeylantern]

perhaps test market your designs/shirts first on Cafe Press or other places like that.

To be honest, I don't think that would be entirely helpful. You won't learn any of the guts of running a business you're supposed to be trialing, nor is the market for DGT the same as the screenprinted market.

It's a little like a grocer trialing a new bricks and mortar store by selling bananas on eBay.