Volkan,
If I were you I wouldn't touch it with a barge-pole.
1). To me it does not read the way I would expect an american citizen to write.
2). Sending five grand for a Twinstar, errr, I don't think so!
3). The one that really sets alarm bells ringing is him asking you to send someone money when YOU are the vendor.
You would be very brave/foolish to be tempted by this

Regards,

Andy E.