The unpublished and extremely rare denomination explains the high price: a laureate denarius rather than the normal radiate antoninianus.
Gosh, yes I'm blind. Thanks for pointing that out (also to Curtis Clay). Of course it is a denarius, which explains the price. I was completely fixed on the reverse.
It's an oddity typical of the Antioch mint, where antoniniani of co-rulers are usually found with the reverse legend ending in AVG instead of AVGG; you can see it, for example, on coins of Philip I&II, Decius & his sons and Gallus & Volusian. Here's an example from my collection: Volusian (251-253), Antoninianus, Antioch mint. Obverse: IMP C C VIB VOLVSIANVS AVG, radiate, draped and cuirassed bust right, seen from behind; Reverse: AEQVITAS AVG, Aequitas standing left, holding scales and cornucopia. Three dots in exergue; RIC 215 Volusian (251-253), Antoninianus, Antioch mint. Obverse: IM C V AF GAL VEND VOLVSIANO AVG, radiate, draped and cuirassed bust right, seen from behind. Two dots beneath; Reverse: AEQVITAS AVGG, Aequitas standing left, holding scales and cornucopia; RIC - The first one is quite common, the second unpublished and possibly unique.
Thanks for the explanation. I have a Philippus I Antoninian of Antioch with AEQVITAS AVGG. I will post a picture later. They seemed to have handled that rather indisciminately at the mint of Antioch.
Here is the picture of the Philip I Arabs Antoninian from the mint of Antioch with the AEQVITAS AVGG reverse. I bought it from the same seller as all the other Ants in this thread. I think this is RIC 82
Here is another Antoninian from this group: IMP M IVL PHILIPPVS AVG // SALVS AVG I have it down as RIC 46. I think that this reverse is scarce.
Apart from the Otacilia Ant at the beginning, this coin is one of the reasons why I bought the group of 20 coins. The portrait of Philip is stunning and I think the coin is kind of scarce. RIC 52
Another early coin, but not so scarce: 31 spec. in Dorchester, 8 spec. in Eauze. With AVGG not AVG on rev. it would be rare: 2 spec. in Dorchester, 1 spec. in Eauze.
Here is a Trebonianus Gallus from that group. Note the beautiful portrait. I think this is RIC 50 in great condition. IMP CAE C VIB TREB GALLVS AVG // LIBERTAS PVBLICA
This Philip I Arabs Antoninian is of a scarcer type. Or if it is not scarce it is at least popular, because it typically fetches quite high prices (RIC 66). I think this coin is the only numismatic reference to the Carpian people. (my pictures are not better than the sales pictures. I have real problems photographing silver coins) IMP PHILIPPVS AVG // VICTORIA CARPICA
I'm wondering a bit about this coin below IMP PHILIPPVS AVG // FELICITAS TEMP It should be RIC 31, but the obverse legend is different. I could not find another exemplar with this obverse and reverse combination.
Künker sold one in 2011 (https://www.acsearch.info/search.html?id=959058), though they did describe it as previously unrecorded. That's the only one I've found.