Marcos,
The PSR 8000 is a good keyboard. But the price you quote is too high right now. A few months ago I was selling the PSR8000 new for the price you are quoting used. And now that there is a PSR 9000 do out in a few weeks with a retail Price of $3100.00 the price of a used PSR8000 should be under $2000.00. I have played the 9000 a few months ago, and it has many new features not found in the 8000, but still has room for improvement. If you read these topics found in this discussion group, you are seing pros and cons of the 9000.
I can tell you, as a Yamaha Dealer, you will see new PSR8000's selling for less than you can buy the used one because Yamaha is lowering the wholesale price to dealers to try to move the remaining inventory out of their wherehouse.
George Kaye