I have stocked a limited supply of the Deep Cut plains mats 6' x 4' in PVC (as well as the normal cloth).
These vinyl gaming mats are hard-wearing, and roll up for storage into the 4' tube in which they are shipped. They can be written on with a dry-wipe marker, and wiped clean with a wet cloth. They are a lot heavier than their cloth equivalents, so unfortunately, I can only post them to U.K. addresses – however, I can post their lighter cloth mats worldwide.
The PVC mats can be found here.
In cloth, I now stock four designs – plains, fields, wasteland and desert, in various sizes. They can be found here.