If it is in good shape that isn't a bad price. The main issue to watch out for on the original x100s is the sticky aperture blade problem. The blades don't stop down consistently and you will get overexposure. Have the seller set the lens to f5.6 or f8 and take 10 or 20 of the exact same shot in a row outside (single shot mode, not motor drive) and if they all aren't the same exposure the camera probably has sticky aperture blades. You can also see this by watching the camera stop down using the DOF preview function if you set the camera to f8 or f11. Put it in/out of DOF preview a bunch of times in a row and if the opening isn't consistent every time the camera has the problem.
It took 3 tries for me to get a good used x100. Once from a seller here (who refunded the purchase), the second was for KEH and then they exchanged it for another that was fine.
You can see it in this video:
https://flic.kr/p/M7pe4s
Shawn