Klingspor! I'll be up that way next week, hopefully my meeting will be over early, and I can run to their store before they close at 6:00 --- we get a discount, too!
Try onlineindustrialsupply.com Can't vouch for them but prices are right and they have a variety of finer sizes. I use Klingspor exclusively. Never got a bad piece of sandpaper from them!