Newbie! Mercedes 500SEL Help!!

[haris500]

Im very close to buying a black w/ maroon interior 1984 500sel US model. It has 93k miles and is in very good condition. Everything stock, including original full size spare and original mercedes extra wheel. Inspected and new tires. It has records stamped from mercedes dealerships up till 80k and has routine oil changes recorded afterwards. Only has had two owners etc. Im buying it for 4k. Drives great etc. Is this a reasonable price??? Ive seen other s-classes, like 420/560 with no records and no inspection sell for like around 6-7k with similar or less miles on ebay and local. Wondering if the 1984 500sel is a good model vs. the other s-classes. Any issues with a purchase like this that I should be aware of???
Please Help!!!