Have you ever tried making a matt yourself? I have and it worked out a treat. And it is cheap.
I had to make a forrest board for a LotR Mirkwood game ( ...well the Hobbit really, you know the bit with the spiders) and bring it across the states for a convention. It had to have that dark, forboding look with the whole board covered in mossy boulders, dry leaves and fallen trees and branches.
I bought a large piece of burnt umbre synthetic felt and two cans of spray-on tacky glue (the kind you use for mounting photographs). A couple of passes with the cans and a layer of flock, coloured saw dust tea leaves, birch tree seeds, a new passs with the cans and another layer of lighter colored flock, repeat till satisfied. Vacuum the surplus flock and voila!
5 years later and the matt still looks OK since the glue stays tacky. And the areas that grow bald from old age and lack of vitamins are easily repaired.