It isn't that cheap really. That's how much the wreckers(americans) buy the car's for in Japan at most.
The rest is a mark up price so you could have just got an extremely good deal.
I would do a compression and leak down test and then look it over, take off the valve cover, get papers, run car fax, whatever. Then maybe buy it if it was all legit, but really ebay is never legit. A lot of the time their's a catch, you get it 2 days late, you get it on time but its packaged to shit and is probably busted, etc.