I saw a used Specialized Rockhopper yesterday that seemed pretty nice and I wanted to ask you guys some questions:

It is full LX except for the crank which is a "Specialized" crank, are these cranks any good?

It is a hardtail with disc brakes; I know nothing about disc brakes, what should I be looking out for as potential problems?

I don't know the age of the bike nor does the seller (pawnshop) but I am guessing it is about 5 years old and the seller wants 400$CDN for it, does that sound like a good price? It is a red and white colour scheme if that helps anyone identify the year of the bike.

The tires look new and apparently the brakes were serviced recently, apart from that, I cannot see any reasons to spend any money on maitanence in the next few months, is that right?

Should I buy this bike?