It's worth what someone ends up paying for it.

Any competent wrench here could do the same thing to any similar bike. There is little or no market for a shiiny new paint low end USED bike...for $550. The ad does not state anything about new hubs, headset, freewheel, spokes, rims, framesaver, etc. It's not a complete rebuild(my take on a complete rebuild, is new everything).

Most any bike seller has enough common sense to know that nobody wants to dump that much cash into a cheap bike.