Berkshire Choice 800
I found a supplier through the berkshire website. I think they sold more medical supplies but I bought a whole box of 9"x9" (10/pks at 150shts/pk) at about $25/pk which was a third of what I was getting them for through my printer supplier.
I use Berkshire Choice 800 lint free wipes. They're a little less expensive because they don't need to be sterile.