From the picture it looks like the side art has significant blemishes. Not unexpected for the age of the game, mind you, but it certainly hasn't been restored to perfection (i.e. new side art). For $900 I'd expect far better than "pretty good for over 20 years old". Again though, that's just a reflection of what it's worth to me.
Also, I don't want to come across as an expert on trons at all. I have never owned one. I am only a shopper who has been watching for one for a couple of months, and have made some unsuccessful offers. I think the ones that I've seen locally have been over priced, but again, if no one will sell them for "the right price" then what does it matter? It comes down to how much it's worth to you, and how patient you are with regard to waiting for the right deal.