leaking auto gearbox 850

I have been offered to buy a Volvo 850 SE 1995 model for a very good price
( lowest trade in offered by dealer).
Car is fastidiuously maintained. It has 189.000 on the clock. I have noticed
a small leak from the automatic gearbox and perhaps the seal on the shaft
end next to it as well.
Can anyone tell me roughly what I am looking at in terms of repairs and
cost?
One minor detail: I am buying from an family member, I know.......

Thanks

JMJJ Cates