I looked at my local HD for discs for the Ridgid 2610 I bought recently and the 6" disc packs they have were 10 sheets for $6-8. I would have needed at least a few grits so it would have been roughly 30 discs for around $20.
After hearing recommendations for Klingspor on The Wreck, I checked them out and they had a 6" 6-hole bargain pack for $20 delivered. I was surprised by how much I actually got...150 PSA and HL discs in lots more grits than I would have bought, from 40 to 400, in plastic wrapped packs of around 6-8 discs.
The only negative is I don't know which type of sandpaper is in each pack..only the grit is labelled, so I won't know which kind works best. Time go sand stuff for fun... :-)
p.s., dumb question, but you can use PSA discs on a HL pad, right? The Ridgid 2610 has a HL pad, but the manual says nothing about only using HL paper on it. I always bought HL discs for the Porter Cable 333VS I killed...