Fisheye for adaption on Leica M39/Zorki/Fed/Leica M?

[ForenSeil]

Hello
I'm looking for an counterpart of my loved Samyang 8mm Fisheye for new Leica M camera.

I already had the CV 15/4.5, which is very good, but I'm not completly happy with it's "way of distortion" (it's not distortion free and not a fisheye).

I don't care about RF coupling @ </=16mm focal lengths, so adapter solutions would be pleasing. But there are not many other to Leica M adapters and some of them are very expensive.
I know that there are two native Leica M lenses by BelOMA (Peleng 8mm and Zenitar 16mm) but I dislike the circular drawing of the Peleng and the Zenitar has very mixed reputations (inharmonic distortion and fuzzyness due spherical aberration till F11, seems to be best @ F16 ).

Do you have any other suggestions or experiences?
Do you know any ~12-16mm fisheyes which have good price/quality ratio?

My price limit is around 300€ incl. adapter (depends a bit on quality)., the Leitz Fisheye-Elmarit is not an option.
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Cameras in active use: IR/UV modified NEX-5N+EVF, NEX-C3, Pentax Q, Minolta XG9, Moskva 5 6x6 Rangefinder
Lenses in active use:
MF
Samyang 8/2.8 E-Mount, Docter-Optics Olympus 100x 1.25 finite macro lens, Tevidon 16/1.8, Tominon 17/4 (10x Macro), CZJ Tevidon 25/1.4, Novoflex Macro-Noflexar 35/3.5, Minolta MD 50/1.4, Noritsu 50.7/9.5, Samyang 85/1.4, Rodagon 105/5.6, Nikon ED 180/2.8, Novoflex 400/5.6, Celestron 500mm F3.6, Novoflex 600/8
AF:
Sigma 19mm F2.8 E-Mount, Sony SEL50F18

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