*OF COURSE* it's a scam. There is a ton of info on importing Skylines on NICO alone, most of it in this Skyline forum. It is *possible* to get a state registration if you're lucky, but that does not mean it is fed/DOT legal. Motorex can get you into a '90 GT-R for about 30k.
http://www.motorex.net/skyline.html# (Click on the "Conversion Cost" link.)
You will notice that this Ebay seller has "sold" another Skyline recently. The winning bidder has the ID "hotbidder4". Interestingly, this same bidder has bid on another auction by this seller, a Lincoln Town Car. I do not think this is a coincidence. *cough*SHILL*cough*
The seller wants 30% within 48 hours, and the rest "upon delivery of vehicle." Anyone wanna risk that 30%? How did this seller acquire "ALL NEEDED DOT AND EPA APPROVED DOCUMENTS" if the car isn't even in the country yet?