sulla80
The Galvano Boys
Buying ancient coins can be particularly challenging for those just starting out. This can be especially true on EBay as a place where forgeries, counterfeits, fantasy coins, and copies are abundant (see: Fake Sellers List from Warren Esty). Relying on the expertise of reputable dealers is good protection - and even they are fooled some times. Starting with an estimate of ~400K, this coin (not mine) was auctioned by Ars Classica in 2015 for $697,882 (650K Swiss Francs) - it is a rare and genuine coin.

A Roman Republican, Cn. Domitius Ahenobarbus Aureus, mint moving with Ahenobarbus in 41 BC. The coin pictured above is about 8 grams, 20mm. A 2018 NAC sale described another of these as "Exceedingly rare, only twelve specimens known and only the fifth in private hands" and "One of the rarest and most difficult issues of the entire Roman gold series". The coin from 2018 is not quite as nice as the example above in my view, and it sold for $447,489.
Ahenobarbus was the great grandfather of the emperor Nero. Ahenobarbus literally translated from Latin as bronze/copper (aheneus) beard (barba)". There is some debate on this coin about whether the person depicted is the IMPERATOR or an ancestor.
16 years earlier in an NFA auction in 1989, a very similar coin reached a price of $140K. It is perhaps a cautionary tale for those who buy coins on EBay. Expert advice has value, and fakes can pass inspection, even with high levels of expertise. An auction house that stands behind authenticity has value.
The 1989 coin with close examination was condemned as a modern forgery, minted by a group who became known as "The Galvano Boys" and by pseudonyms "Costodoulos" and "Gulyas". They were believed to be operating in Greece.
The forgery was exposed by Silvia Hurter and Alan Walker and published in the "Bulletin on Counterfeits". Both are impressive experts:
The British Museum Forgers, or, "Costodoulos" and "Gulýas" BoC 17, no.1, 1992, S.2-48.
The Galvano Boys - Part II BoC 17, no.2, 1992/3, S.2-11.
The forgers were initially called the “The British Museum Forgers” because some of their dies were created from casts of electrotypes of coins from the British Museum. The pair also made their own original engraved dies and enhanced transfer dies from genuine ancient coins. They were renamed to the "Galvano Boys" when the British Museum challenged the use of their name in reference to the forgers. The Ahenobarbous Aureus was reported to be a copy from a British Museum electrotype. The British Museum began selling electrotype copies of coins in its collection in the 1850s.
Dealers who were misled contacted the purchasers and refunded their money, but the forgers were still active years later.
I have a denarius from a relative of this Ahenobarbus. It is a denarius issued about 90 years earlier in 128 BC by another Gnaeus Domitianus Ahenobarbus. Crawford writes that the grain ear on the obverse and the wild beast fight on the reverse appear to represent grain distributions and games offered by an aedile to advance to higher office. Although it is well struck, and has some gold/iridescent toning, this coin is a more commonly available coin with Crawford reporting 71 obverse dies. For a comparison on rarity there are ten times as many - 750 obverse dies - reported for Julius Caesar's popular elephant trampling snake/dragon denarius Crawford 443). This coin came from CNG.

Roman Republican, Cn. Domitius Ahenobarbus, 128 BC. AR denarius, Rome mint
Obv: Helmeted head of Roma right, grain ear to left; mark of value to lower right.
Rev: ROMA / CN DOM, Victory driving biga right; below, man spearing lion
Ref: Crawford 261/1.
As this coin was issued, Rome was on the brink of a Social War, Civil War between Marius and Sulla, and a series of "Mithridatic Wars" with the King of Pontus in Asia Minor.
References
A short overview of "How ancient coins were made"
Silvia Mani Hurter Bibliography
2009 Numismatics.org Obituary Silvia Hurter
The Celator Vol 3, No. 7, July 1989, p.V. Ad for Numismatic Fine Arts Auction XXII – has a photo of the Galvano Boys Ahenobarbus coin
Dr. Ilya Popov’s Fake Ancient Coin Reports Note: reference to IAPN BOC Vol 17, No. 1 in 1992 - Example 17
IAPN BOC on FogeryNetwork.com
British Museum electrotype sold at auction