The books would be in storage with LCS owners that bought the stock as the stores went under during the 90s purge. I can remember seeing a small part time dealer land a bunch of books like this in 2000 or 2001 that resulted in him having to rent a larger space to sell out of. There was some great stuff in it - the books came from the owners of a LCS that sold out in the early 90s peak but had stuff in storage that was not included in the deal (or maybe it was but they did not turn it over). Needless to say, they cherrypicked the best stock (likely was supposed to have been included in the deal) - there was a long box of Secret Wars #8s (selling for $10 apiece), longs of McSpidey #1s (selling for $4 apiece) , two shorts of ASM #300 (selling for $40 apiece), a long box of Wolverine #1s (1980 regular series - selling for $20 each), a short and a bit of NM #98 (selling for $10 apiece ) and all sorts of other hot late 80s and early 90s Marvel books. I bought a few of each and submitted the best copy during the early days of CGC when they were much harsher on Copper/Modern books, but foolishly did not go back for more when they only graded out 9.2-9.4. Hindsight being 20/20 I should have bought them all, but back then he had way better SA and BA stuff and the copper/modern books did not move well.
A year or so later the same dealer landed another store stock group from the same seller. It was mostly early 90s drek, but there was a ton of pre-unity/retailer incentive/late run Valiant in it. I helped him move some of it in for first crack at it. There was a long box or more of Rai #0s that we laughed about as being trash like the longs with Turok #1, Bloodshot #1, Ninkak #1, etc. I debated buying the long box of Rai #0s for cheap along with the better stuff (which was still dirt cheap - I paid $5 for the Harbinger #0 Pinks but the rest were dollar books or less) since I liked the story, but passed. It was the smart move up until earlier this year, I guess.