This is something that I also thought like one year ago! And I think that actually some pads companies do the same, so why not us?
Looking at some old VIZ brand pads that I have, there is written "hardness 85" and I'm really sure that is polyurethane with that shore... I remember that them were too hard, maybe trying with less shore..
I also contacted with some local companies, but only offers big sheet, the good was that I could choose colors besides to the shore.
Have you got any link for ebay PU?