Have you tried Inked Playmats? I don't know if they do any that small, but they make good stuff, allow for customization and are usually pretty fast. And I've never seen them require a big batch order.
I will have to check them out. I was talking with I think Mouspads.com...but their prices are insane. They wanted $500 for one mouspad of each of the 4 main Martian Coaster colors. There is no way I am going to pay $125 per mouspad for a little 4x4 square of fabric so I am back to looking for a vendor. I will try this one you linked next. I already sent them an email asking if they can do 4x4 sizes. I love martian coasters and really hope I can find someone to do the mouspad version of the coasters for an easily packed and carried version to go into my emergency kit.
Have you thought of doing a 9x8 sized one with all four colors in the four corners and then cutting them apart?
The only local print shop I know of is Kinkos lol.
I will have to try Office Depot....closest Office Max is like 70 miles away. Way too far to drive in a Gas Guzzling tank of a vehicle.