Searching for "fogged paper" auctions probably won't get you very far because most people selling old paper, at least in my experience, find it at estate sales and such and don't know if it's fogged or not.
I'd say search for regular photographic paper instead. You'll get more hits and will probably find some large lots of 8x10 paper for cheap. Last month I picked up a bunch of photo paper from 1988 that really isn't fogged much at all, but another recent purchase of Kodak paper from 2004 was fogged pretty badly, but it's great for paper negs! Counting on old paper to be fogged is a crap shoot. As mentioned above, you can always pre-flash your own.