I am upgrading from 105 to Ultegra bottom bracket, crankset, rear derailleur, and front derailleur. The 105 components only have about 400 miles on them. My LBS told me they would give me $80 on trade-in for the 105 components I am replacing. I really have no intention of ever building a bike, but I kind of wondered if I should keep the stuff just in case. Let me know what you think. Is it worth keeping the stuff around? Thanks, ROn