I personally think the M60 engine just got a bad rep because of the Nikasil problems. The only real problems it causes are (1) makes a lot of things hard to do in the engine compartment, because it takes up so much space, and (2) if the car is an auto, that's an awful lot of torque to be battering an auto trans.
If it's an automatic, I'd say it would have to be in exceptional condition, in and out, to fetch 13K - with all maintenance records and recent replacement of thrust-arm bushings, subframe bushings, dogbones, radiator, etc. These are the things that will definitely go on you.

BTW, I'm biased, just buy my 530iA for half that much.