See http://www.om-labor.de : "Sale, repair, refurbishment, customization, dslr adaption of OM-system components." This is the location of their "lab": https://www.google.com/maps/place/Beethovenstra%C3%9Fe+51,+60325+Frankfurt+am+Main,+Duitsland/@50.117242,8.65637,3a,75y,279.11h,105.37t/data=!3m7!1e1!3m5!1sicejHmlE-uMjzzcgbz7vIg!2e0!6s%2F%2Fgeo0.ggpht.com%2Fcbk%3Fcb_client%3Dmaps_sv.tactile%26output%3Dthumbnail%26thumb%3D2%26panoid%3DicejHmlE-uMjzzcgbz7vIg%26w%3D374%26h%3D75%26yaw%3D343%26pitch%3D0%26thumbfov%3D120%26ll%3D50.117242,8.656370!7i13312!8i6656!4m2!3m1!1s0x47bd09500aa38e2b:0xd85ac61df1909aa!6m1!1e1

Bought a 21mm f3.5 from them and I like it. Not only looking special from the outside, but the glass is like new too.

Well, of course the looks are not really needed, but they seem to have access to some very good glass, maybe old new stock? They have been in the service business for Olympus before.

These days it's getting harder to find a really good Oly 21mm, since it's the second best vintage prime in that length and the best – the Zeiss C/Y 21mm – is fetching incredible prices. Plus, the Oly is the smallest and lightest from that time.

You should contact them about prices for unpolished ones with good glass, they seem to have more stock.