I paid $100 for my 917. It had less rust, but more wear & tear. As I later found out a dented & cracked hood that would get hit by knives (which they removed). Cut out the bad hood & patched it. New knives, belts & PTO shaft. Still have yet to fix the Crack between the spar & hood. Roller brackets are welded on & no longer adjustable.
The bearing and/or bearing mount between the rotor & pulley blew on a recent job. Have yet to dig into replace that.
Knowing what I know now I wouldn't have paid $100 for it... I'd probably have gone to $500-600, then put in the same $400 in parts & 2 weekends work on it I already have. I'm looking at replacing mine with something newer (probably rough cut), but will still keep it as a spare and/or for a better cut on more lawn type stuff.