Why would you have to spend a lot? For $1500, you can get a nice 17-19 pound name-brand CF bike with 105 groupset. You'll probably have FSA Cranks and a bit heavier wheels -- that's where the $1500 price comes in. Put the extra (when you get it) into a wheelset if that's your fancy. No one will convince me that Ultegra shifts 'better' than 105 -- it just weighs less, and to be completely honest, I'm mostly convinced that the 105 being heavier, that it will last longer anyway.