You can't go wrong buying fron an authorized daler.
"Warranty Policies. Yamaha provides warranty coverage for new Yamahaź products originally sold by Yamaha Authorized Dealers located in the United States. Check our DEALER LOCATOR for a list of U.S. Authorized Dealers. Yamaha products purchased from retailers other than Yamaha Authorized Dealers (whether via the Internet, or otherwise) will NOT be covered by Yamaha’s warranties, and U.S. service centers will not repair such products under warranty."
If you have any doubts as to wether a dealer is authorized, check out the DEALER LOCATOR in this link.
http://www.yamaha.com/warranty_safety.asp