I recently found an old letter from Jim Atwood. It was about arranging the deal for my purchase of my first copy of the Children of the Mushroom 45.
I couldn't even begin to list all the great LPs and 45s I got from Bill Paquin. He was a good friend who is really missed.
An interesting, but spotty source for 45s were the old Metro Music catalogs. The grading was beyond erratic, but just as a record graded Mint would be G+, a G+ record could be VG or VG+. And mixed in with the overpriced records, I scored Evil I and Cosmic Rock Show for $38 each. Both were examples of his erratic grading (G+ being much better, especially after cleaning).
I also loved the original Midnight catalogs from before they opened the store. They were mostly LPs, but also had a few singles sprinkled in, like Arrogance "An Estimation" ($18). Had no clue what it was, but it was probably my best purchase ever from them, except maybe when the store opened and I found a copy of the Beauregard LP on the wall on my first visit.
A couple of great sources for private press LPs were the GM ads of Randy Jadwin, Jim Allfrey, Lloyd Okaji (got one of his mid-80s lists I should scan and post , if there's interest), the Michelson Bros. aka Local Favorites and Chuck Warner when he was still doing the Kinkdom ads and catalogs. Bought my first C.A. Quintet from one of the lists. When I got heavily into punk & hardcore in the beginning of the 90s, those lists Gregor mentioned were like encyclopedias for me (in a way, they still are). Chuck's a great guy, and I always looked forward to catching him at FMU each year (though he missed the last one, probably because of dealing with the fires).