Home Depot has this material on rolls in several different patterns and thicknesses, so for a very few bucks you can experiment. Rite-Aid drugs also sells 5' rolls of this in a few different thicknesses and colors pretty cheap. I got started by getting a 5'x1' roll at Walgreen's for $1. That's 20 cents per mat.
They do work pretty well, and you can use them in several different ways, such as under or on top of another mat. For a long time I was using the standard Technics rubber mat upside down with one of these drawer liners on top of it. Later I went to an Oracle Groove Isolator with a shelf liner on top. Now I'm using the Groove Isolator over a felt mat, but without the shelf liner.
On my rig, I eventually found that the thinner mat emphasized leading edges, but a little too much, and the thicker one was just a little too dull. It could have been related to changes in VTA, however.
Either way, it's cheap enough that you can cut yourself a bunch in different thicknesses and have some fun experimenting. I did found that the thin one made music more compelling and danceable.
