99% of NSX related "international" buyer and sellers for high end cars are scams.
If you think you have a real car for sale/ or serious buyer, just post the location & the members in this forum can check it out for you.
When selling, I tell any inquiries (aka nigerian scammers) that I'll pick them up at the airport. If they like it, I accept cash only. Funny enough, I've never had to pick somebody up at the airport.
When buying out of country, I have a local check it out first before wasting any time on a likely non-existent car.
Once you have a deal on a real car, the shipping part is relatively easy. You can PM me if you need shipping help I've shipped quite a few cars half way around the world (as seller and buyer). Figure $1500-5000 by secured container, depending on how far it is coming from or going to. The shipping expense kills most deals on cheaper cars (ie under $30K).