I don't think that is too much... it's a lot cheeper than some of the high quality brands.
I use MicroMesh products a lot,
http://www.micro-surface.com/default.cfm?page_id=1 and they are about $10 per 12X12 sheet. BUt they are soft cloth.
The thing to check on is how much grit comes loose on your work while sanding it.
naplak Modeling
naplak.com/modeling
www.naplak.com/modeling ... a free site for modelers
www.scalehobby.com/forum/index.php ... a nice Modeling Forum