AFAIK you can get these front-elements repolished, but I am not sure if you can get them re-coated.
If you do get it repolished, you might want to consider using a UV filter. I slapped on one on both of my Summicrons (collapsible LTM summicron and a dual-range, both with pretty much prefect glass, albeit expensive purchases)
No idea about expenses, since where I live, there are no Leica-dudes to send stuff too, so I mend the lenses myself (simple CLA), cameras just needs to work before I get them, fiddling with the shutter and rangefinder-optics seems rather scary.
I have a IIIf where the self-timer isn't engaging the shutter and I am very skeptical about fixing it....from seeing the service manual, it seems to be many things that can go wrong.