Steady rest is a good thing, I see a lot of lathes sold without one. You can easily spend $150-200 to get one later, so there is 1/3-1/2 what you are paying right there.
It looks dirty and crusty but actually not bad, buy a bucket of your favorite grease cleaner and it will probably look pretty good when you get done with it. I would suggest telling the seller you will buy it at their price on Saturday barring obvious damage he didn't tell you about. At $450 I don't see you losing money even if it turns out to just be good for parts. I'm not seeing this as just a parts machine.