I have a large quantity of 8.5 x 11" page protectors; all appear to be Staples/Avery or better quality and all are in very good condition (no tears, nor creases, no stickers/labels, no yellowing). Of course the rub here is the potential shipping costs but after playing around with this I think the best method would be a Regional Rate B box since it will fit 500+ just fine (USA only). The Regional Rates should make sense for much of the country, but the West coast might not be feasible.
So here is the deal if anyone is interested… a box of 500 for $19.00 plus actual shipping cost. I live in Western North Carolina (zip code 28739). You can easily calculate the Regional Rate cost with this USPS link https://postcalc.usps.com/DomesticZoneChart
then click the 'Get Zone for ZIP Code Pair' tab, enter my zip 29739 and your zip code. This will tell you the Zone, then refer to the zone chart below to understand cost.