Last summer I offered to make and sell some T-shirts but only got a few takers.
I can print your choice of ink color on your choice of shirt color, as long as they are "standard" and commonly available.
Orange on black would be considered the default. For an additional $2 I will do a double print, which can be on the back or as a contrasting color, shifted slightly, to create a shadow effect. Black on white with an orange "under-shadow" is pretty sharp.
$16 shipped domestic US, $29 shipped international. I know everybody hates international shipping, and I can't understand why it should cost $17 postage just to send a T-shirt in an envelope to England, but it does.
Deskthority shirts are available, too.