Aemilian - Augustus of Imperium Romanum from August AD 253 to October AD 253
Aemilianus, also known as Aemilian, was Roman Emperor for three months in 253.

Commander of the Moesian troops, he obtained an important victory against the invading Goths and was, for this reason, acclaimed Emperor by his army. He then moved quickly to Italy, where he defeated Emperor Trebonianus Gallus, only to be killed by his own men when another general, Valerian, proclaimed himself Emperor and moved against Aemilian with a larger army.

With only three months in power, coins of Aemilian are definitely comparatively scarce - and expensive - compared to the rulers immediately before and after him.
Aemilian
Emperor Aemilian of the Roman Empire

(1) Aemilian 253 AD
AE unit Viminacium
Obverse: IMP C EMIL EMILIANO AVG, drap. bust with laur. head right
Reverse: PMSC - OLVIM, Moesia standing between bull and Lion, AN XIV in exergue
Ref: Pick 180
(2) Aemilian AD 253
Obverse: IMP CAES AEMILIANVS P F AVG, radiate, draped and cuirassed bust right
Reverse: PACI AVG, Pax standing left, holding olive branch and transverse sceptre, with legs crossed, leaning on column
Ref: RIC 19