There was a time when that would freak me out. Now I am more experienced and realize that could be a trivial problem. If its leaving a puddle under the car I'd have to fix it soon. That looks like a bit of seepage that I would keep an eye on.
I would not hesitate buying a car with some seepage - it's just a seal. Mine was the same when I bought it. Ended up not being the RMS - it was the IMS flange - and no, a seeping IMS flange does not indicate an impending IMS bearing failure.
Negotiate a price that includes the cost of repair. Obviously make sure the rest of the car has no surprises.