Arbitrarily, it's not a bad deal... but you're going to be investing a good deal of time and effort to clean that mess up.
This is a hobby... I always recommend, when it comes to something you do for enjoyment, that you get what you want, rather than what is cheap. If a rebuilt 90 is what you want, great! If you're really wanting something else, you're far better off saving for what you really want than buying something you don't want because it's cheap. Yeah, buying what you really want might be expensive... but it's less so than buying twice.
You're looking at what, about a grand worth of equipment there, brand new? Looks to me as if you need to build (or buy) a new stand, re-plumb, many hours of cleaning... maybe reseal the tank. How much is your time worth? When you get all the work done, are you going to be happy with the result?
Questions only you can answer.