It is always helpfull to someone. Just figure that Engine parts, SAY you buy an 07 Ulysses-Tranny parts and Lights depending on models and so on will fit. Engine parts are closly related. IT's the Electrical areas like ECM/Electrical Harness Temperature sender and other Electrical parts Etc..that is critical and make sure to install right away.
The Buells will Have some parts around for 20/years to come. The Inner Transmission Parts are closely related,w/ the sporster so you can always mix if needed. It really Depends on what you need.
If you buy a 2006 OR 2007 Ulysses then maybe buy some of the Harder Parts like Harness,Cluster,Swing Arm Materials etc. Wear Items are what keeps you Riding! If you buy an Electrical item put it on right away and save the used part you now know it works. Look Around Before you buy, then find places with Wrecked Bikes like yours that run etc.. that you want, for Once you purchase the Bike you then have an Idea what you are getting your money into. Always check out Availibility of Outer Parts such as plastics and the cosmetics' areas as well.*Jimi