Oh, quit your grumbling about the prices. You'd pay twice that for a concert T-shirt.

I paid $15 for my black Parker logo T-shirt a couple years ago on eBay (plus the shipping cost from the UK).
...though I would ask Parker to look into the whole, "if it fits, it ships" thing that the USPS does. That might be cheaper (especially if you buy a couple shirts).
That said, I'm still really glad there's a place to get them now (though the selection is limited). I'd love a classic gray T-shirt with a black "Parker Guitars" logo, in case anyone from Parker is watching this. As soon as that's an option, I'll place an immediate order.