525i Head

So far, I've removed everything except the head (awaiting tools via snail mail by next Monday).
Although I won't know until I take the head to a machine shop, I did call one place and explained to him the #3 cylinder is taking in coolant. He told me it's most likely cracked at the exhaust port of that cylinder, very common for M50's, and said he could repair it for $850 which includes the rest of the required work such as decking if necessary, valves, etc.

Does this sound like a reasonable price?

Are M50 heads repairable?

Like I said, don't know if this will be the case but I want to be prepared when it does go into the shop sometime next week.

I've decided I want to keep this car being that I've maintained it extremely well, both cosmetically and mechanically.

Thanks