Put your money in the wheels. On a tri bike aerodynamics is more important than weight. So if you're on a limited budget, don't blow it on Durace componets and carbon fiber bars. (Those things are nice, but not necessary) Buy a durable set of training wheels, then a disc and a trispoke (or deep dish CF wheels) then spend what you have left on componets. You'll be faster with 105 componets, cheap bars, cheap seat post and aero wheels, than you'd be with D/A componets, and CF bars, seatpost etc, and standard wheels.