$200 is about right around here as well IF the bore is good, maybe a bit more if it’s from one of the better makers.
The question is what your buddy wants to do with this rifle and what he’s willing to spend and do to get there. European 8x57 ammo is expensive but it can hang with the 30-06. American 8x57 ammo cheaper but it’s loaded about like a 300 Savage. Handloads are cheap and can match European ammo, and that’s really the best way to go in this case.
The bigger issue is that this rifle has no sights and will be useless until it gets them.
The cheapest bet is to re-install original military sights, which are rugged, cheap, functional, and widely available. He could probably get parts for $100 (shipping and taxes REALLY wreck the economics of a deal like this) and do the work himself, but then he’s $300 into an iron-sighted military Mauser in a no-name stock. Not sure that’s where I’d want to be, especially since it could take considerable work to get it zeroed with a commonly-available load.
Adding commercial iron sights is not as cheap as it used to be. I’d budget $200 for parts and labor, but gunsmiths are uncommon around here and this work may less expensive somewhere else. Then he’d have $400 into an iron-sighted military Mauser—again, not necessarily a place I’d want to be.
Adding a Scout scope with an XS rail (
https://xssights.com/mauser-clifton-scout-mount-rails/) requires modifying the stock. Total for parts and labor is probably close to $200 around here, and he still needs to buy a scope. Total investment for this gets really close to $650 but at least you'd have a workable rifle.
The work to mount a scope includes drilling and tapping the receiver and modifying the bolt handle. Parts include rings, bases, and a new safety. I think it would be hard to go this route for less than $200, and $300 is probably more like it. And once that’s done, you still need to buy the scope itself. Low end on that is probably $250, so the total cost looks more like $750 unless he gets lucky and scores the right parts for cheap. He'd have a rugged, useful hunting rifle when he’s done, but he could have bought a used commercial sporter with a decent scope and chambered for a common cartridge for that much money.
No matter what he does, I'd expect to wait at least a couple of months to get the rifle back from the smith--not because the work takes that long but because he'd have to get in line.
Making this rifle usable is probably not worth the cost unless your buddy can do all or most of the work himself.
All of this assumes that the bore is still good AND that there are no issues with the stock and bedding. If not, then it’s a $50 rifle.
Okie John