You should have this place inspected by a competent home inspector. To
need a sump pump in a crawl space is not typical and I'd want to make
sure where the water is coming from, how it;s getting there, etc. If
the place is properly graded, you would have to have a very high water
table to need a sump pump in a crawl space. And you want to be sure
the pump wasn;t added after a lot of moisture problems already did
damage, ie rot, mold, etc.

It's possible the sump pump is not even usually needed, just there for
the once in 20 year exceptional rain, but I'd make sure to find out
what's going on, before you buy.

As already pointed out, sump pumps are cheap to replace and operate and
require no maintenance.