I can see having a local designer being an advantage but only really if you get custom orders. I checked with a few online vendors to get my pricing, mind you that is not a guarantee of the quality I just chose the morning St expensive options for the shirt and ink. Not waiting for the order is a nice advantage as well as not having to pre-order (for that price I needed to make a minimum order of 6 t-shirts).
You don't have to prove you can multitask to me, I've been witness for long enough. I was more concerned you were going to lean on this as a primary revenue stream to make progress and wanted to point out some concerns.