Well if you noticed quite a few are talking about going to thrift shops and GW. There you will basical find crap the record stores don't want to buy, and if they don't want it it has no value to most people.
GW is getting harder to find good stuff, that's why I spend more time at less well known thrifts.
While your assertion is generally true, in the last three months I've found the following:
The Best of Little Walter, Chess, VG+, 75 cents.
Blonde on Blonde, NM, $1.00
The Reiner Sound, Fritz Reiner, Shaded Dog Living Stereo, NM-, 40 cents
96 Tears, ? and the Mysterians, VG+ $1.00
The Fleetwoods Golden Hits, VG+ 25 cents
You have to go through 1,000-2,000 to get one jewel, but they are still out there.