MirkaGold Pro Flex 9 X 11 P120 (50Pc)

This is the only brand of paper we use in our shop (high-end picture frames). There are cheaper papers out there but they wear out so fast that they end up being more expensive. In my experience this paper lasts longer, costs less, and loads less quickly than the comparable Norton or 3M product. Also, we spray water-based finishes and this paper is fully compatible with them—zero fish-eye in the finish from stearates or silicone oil.

Seems to last a long time. Sands quickly and efficiently. You'll like using it.