personally on my latest bike i spent $750 on the bike (retail $1,500) and so far have spent right at $1k so far on upgrades (seat, brakes, tires, wheels, pedals). I plan to upgrade a few more things including componens, bars, stem, and seatpost and that should run me close to another $1k. The only reason i can justify spending so much on this bike is that i plan to move the parts over to a new frameset later. Plus i really like the frame anyways. I also enjoy making a bike my own and not just something off the shelf.