The Konica AR 2.8/15mm Fisheye is a quite rare and relatively expensive lens; obviously Konica collectors are willing to pay as much as CHF/EUR/USD 300-500.-- for a nice looking sample. I have seen the lens only once, but was not able to test it. Any commentaries on its performance are welcome!

 

Konica Hexanon AR 15mm f28 Fisheye section
 
KONICA HEXANON 15mm 1:2.8 Fisheye                 
(10 Linsen / 7 Glieder)