I use 3m spray adhesive for my 10 inch disk sander and it works just fine-- just make sure you use an adhesive remover (I like goo gone) to remove all the residue and clean it well with 409 or such between uses.
I cut mine to size ahead of time with a wooden disk I made just undersized and I use a utility knife to cut it (sandy side up so that it grips the wooden disk tightly) The scraps I use are the bigger ones from my klingspor "bargain box" and the sandpaper lasts a loooong time between uses as it is quite heavy duty.
speaking of klingspor, you could always just buy paper from them here
http://www.woodworkingshop.com/cgi-bin/ ... roup=DISCS
still pricy, but cheaper than you were looking at and if you watch from time to time they will do free shipping on orders over $25
Lawrence