Like always, value is whatever someone is willing to pay. But I'd think no more than $50 (and probably even lower due to the flood) for a machine that isn't particularly rare and it having something like that happen. A lot depends on how far up the water went in the machine. But if the seller wants much for it I would pass, there are too many other machines available to take on this one with this history. But that's just me.
Some parts like the glass, chrome and stainless metal, plastic pieces may not have been harmed by the water, but all connectors, ground connections, the insides of switches, hopper motor, etc will probably get a layer of rust soon and things can be very intermittent after that. If you are going to use the machine for parts to go on other machines then each part that gets removed could be inspected as you use it, that would reduce the job to a smaller level. But I'd be real leery about thinking this will be a snap. It may work fine for a while after drying it out, but longterm I would think there will be problems. There's a reason submerged cars can only get a salvage title after a flood.
If you wanted to just use it as a room decoration, like something vintage in a game room, and not expect it to play then that can be done pretty easy. The general lighting can be made to work easily and it will look like any other machine.