The Dirt Merchants was "unearthed" (clank:BOOM) circa 2005/6. No one that I knew had ever heard of the songs before. The first copy was offered on ebay; I lost out to Toddophonic Todd.
Ditto for the Hotbeats 45. Dealer Chris C. from Long Island brought the first known copy to the Allentown all 45rpm record show, this was about 15 years ago as well. He spun it for a couple of like-minded fiends after I heard both sides, and the bidding frenzy began. I managed to come away the victor, however, upon returning home and spinning it I found the copy suffered from groove distortion in the high volume peak areas, and during the guitar break. I ended up trading it away to one of the guys who competed for the copy. Until Jason L. managed to purchase three unplayed copies (one is finally in the collection), all of the Hotbeats 45s that have turned up in the wild, offered on ebay, etc. suffered from groove distortion to varying degrees. The unplayed copies play perfectly.
The Jazzmasters 45 was a deaf buy (took a chance on it without hearing it) from a doo-wop specialist dealer, my notes say I bought it in 2002.
Another collector who posts here occasionally found a copy in a junk shop(?) for peanuts a decade ago or more. When Bill N. found the D&C label owner, he had quantity on the Oscar Five, the Continentals, the Panthers (on the D&C label but pressed in Canada) and maybe 5 copies of the Chancellors. There were no Jazzmasters 45s, Bill said the label owner never even mentioned the record, he must've totally forgotten about it.Based upon that, I bought the copy, and lucky me, bonafide killer!
The most recent totally unknown "killer" (rated at least a 6) is an unknown 45 that a dealer recently auctioned by St. Christopher's Children. Both sides are stellar. Seems to be a NorCal location. Lots of 45s that I never heard of have surfaced since publication of TBM, but hardly any rate higher than a 5 at best after we voted on each. The unreleased acetate sides sometimes reach the 6 rating plateau. As mentioned previously, the Society acetate songs discovered a couple years ago have rated higher.