I was able to use one of those $100.00 specials, and believe it or not, there is a marked difference if you are going to be at your lathe for 8 hours.
Since most of us don't, I agree, and use both the green Woodcraft model in parts of my shop and the puzzle piece one in other areas.
The other thing that might help is to make sure you have a good set of footwear with a good set of inserts.
I tried a set from my company shoestore, they cost $25.00, but I don't even need the mat any more. I still use the mat, because changing the height of my oneway can be a pain, and I am at the right height for me with the mat.
The insole is made of the same stuff as some of the better floor mats, but with enough stickyness on the bottom, to not slide in your shoe like some of the more readily available commercial ones. The first pair I have is almost two years old, the odor block works good (I don't have the EPA coming to the house when I take my shoes off), and they still have alot of cushion to them.
Talked a friend in to trying a set, he has a bad back and hip replaced, and he says they are fantastic, and he can work at his lathe longer.
Just my .02
Jerry