Hotz Mats has a variety of felt mats mono-colored or with additonal airbrushed details like fields, moon craters, rubble and similar. Hex and Square grid printing is optional and available on both sides in multiple sizes.
http://www.hotzmats.com/1_mat_info_page.htmlI had two mats, one green and one desert brown in 4x6. Quality is good, although if you just need a simple mat without any effects or grid then a sheet of felt from the local fabric store is much cheaper. Be aware that the time from ordering until it arrives at your door is hit-or-miss; I ordered from Germany and it only took about two weeks from the U.S., but others had order times of multiple months even when ordering from within the U.S.. In the end however, I think everyone gets their order, it's just that Hots seems to work in batches and if your orders falls between a batch processing session, then you might have to wait.