Base bars

This year I have decided to try my hand at building up my own triathlon bike. The frame is purchased, drivetrain almost complete. Now it's time to look at the cockpit, so here is where I would like some advice. Is it better to buy a complete system or purchase the base bar and aero bar separately? The one advantage I can see to buying them separately, is I could use my Profile Design t3 aero base bars from my road bike, which I already know work well for me. However, that would leave the question, what base bar would they work with?
The one thing to keep in mind, is that I'm on a budget. While the bike doesn't have to be done next month, I don't want to save for a year just to buy a ridiculously light and aero front end.