For smaller prints a cheap release paper substitite is the remains of label pages. The silicon like coating on the paper that labels are adhered to works quite fine for me for dry mounting prints to 8x10.

That lets me save the few larger sizes of proper release paper for the big prints.

I know proper release paper is available by the roll, but when pricing it a few years ago, it struck me as quite expensive for the smallest roll given the small amount I actually need.