Well, some not-so-great news to report here. I checked in again with Shadows Embroidery who is doing the shirts for us. The conversation was not too productive. They claim to have spoken to USPS and UPS about better (cheaper) shipping options with no progress. They say their mail delivery person will not pick up any shipping envelopes or boxes, and that the boxes themselves they can't get ahead of time. Further, the handling of said shipping options is outside their normal procedures. They like to work only with FedEx, who will pick up their stuff at their office. They assured me they make no money on the shipping options and are not in the shipping business. I get their point, but yet, I told them we were disappointed with the current options and would seek other companies in the future. Then they went on a justification rant about how their prices are competitive, they didn't charge to set up the webstore, etc.
I think they are used to large orders where single shipping costs of $12-18 feels reasonable. For the purchase of a single shirt or two, I don't think it's reasonable. Perhaps if people wanted to voice their wishes they could email them: email@example.com or post to their Facebook or Tweet them or whatever.
Again, sorry for the hassle for everyone who wants one but doesn't want to pay shipping (understandably). We will look into other options next spring!