Most of the time they usually sell the individual parts on a motorcycle like the plastic fairings, etc. Ebay is the easiest way for it. The other day I saw an ad on ebay for the entire plastic fairing set for a 2004 r6.
All you really need is a frame with a clean VIN and swap the rest of the parts over. Its still a risk with the number on the motor turning up hot, but I'm sure many people will take the risk. Theres ways around everything