And where are you getting the rest. Best deal on frame I've seen new is around $500 but that's with shop race team insider deal, on ebay it's hard to find a CAAD frameset for less than $500 used. Best I've seen for new Di2 is around $1150.

But none of that really matters, the main questions I guess is everything going to be new if you build the bike? Is your build going to be better than the stock CAAD 10 black? Are you using better wheels, different components that you like more than what comes stock? All things being equal if it costs the same I'd much rather get the complete from an LBS with full warranty and shop support