Your Metapontion nomos of Demeter is of course stunning and beautiful. Also, apparently just the right price. It appears the estimates for these rare nomos masterpieces became more accurate by triton 22, but only after a ridiculously low estimate in 17, followed by an excessively high estimate in 21. If there was a 'cursed winner' during the your magna-graecia section it was perhaps lot 340 selling for 10x the starting price.
Pprp made a hypothesis but I believe it to be incorrect. The coin was from a J Gomer collection and it along with some 33 other Greek coins were sold in Triton XXI. The coins ranged from fairly large group from Greek Italy to a couple of electrum staters from Kyzikos. It looks like the collector was simply selling either all or part of his collection. My suspicion is that my coin "fell between the cracks". I have similar things happen to me in an auction though not with such a spectacular loss. In one auction I had two siligua of the later empire both were estimated at $100 dollars. The first one died got one bid so it sold at $60. The second one went for $600 Valentinian II Ar Siliqua Lugdunum mint This is no longer my coin I should note that auctions are basically a crap shoot. You just really do not know.
Always make sure you have a stiff drink next to you as the hammer strikes to help you through any losses
You may be right! As I said that was only a hypothesis; I do remember several coins of these dies popping up in the past 2 years, but all are far inferior to yours. On the other hand, I recently bought a coin from Triton that I am pretty sure was damped at a low price -given the current market circumstances- because it was supposed to be unique but then a 2nd appeared. Several nice owl tets were damped -by informed people- in the market just before the hoard came in. I don't know who is/was J.L.Gomer and I haven't seen any other coins of him except from that sale so I can't tell if this was part of the whole of his collection. It seems however that the majority of the coins auctioned in that Triton under the Gomer collection provenance were bought just 1-5 years earlier.