RobotShop claims to have some in stock as well:
http://www.robotshop.com/banebots-p6...-grease-4.html
Plus some other combinations of them. I just had my facilitator quiz them and they don't have any 20:1 or 81:1 in stock in any flavor, despite the claims on the website. They claim they have the gearboxes but not the motors for some of the motor+gearbox combos, and they're not willing to split up the combo. You're welcome to try to talk sense into them, but I don't need those badly enough to try to force a company to take my money when they so obviously don't want it.