Bike looks pretty good in the pictures - $3K seems very fair. I don't know of any W650-specific exhaust systems here in the US -- though there may be some of which I am not aware. There are several systems available in Japan and Europe. The best sounding one I have heard (on YouTube) is made by a Japanese company called Posh-Faith.
06 Suzuki DR650SE
04 Yamaha FZ1
90 Honda Hawk GT, 00 Kawasaki W650
79 Honda CBX
82 Honda CB900F