I'd say that $2400 is a decent price, without seeing it to revise that estimate.
It should have all the bits, though may possibly need things like shocks, tune
ups, carb cleans, fork rebuild and/or brakes at that point. If they have any
records of maintenance, that could be cause to adjust the value upward a bit.
I paid very close to $2400 for my '82 LS with 15K original miles, all guages working, sidecovers, etc.
though it has definitely required alot of cleanup and adjustment, rebuilding of the usual
stuff (Forks, brakes, etc), replacing rubber grommets, filters, etc. at that.
Having experienced it myself, I'd recommend that if you buy it that you pull the tranny
and do a spline inspection and lube along with changing all the fluids and filters right off
the bat...