I'd avoid the bikes on BikesDirect. I don't think the brands are quality brands, certainly not brands who've put any thought into what makes good tri bike design. The other thing is BikesDirect bikes come bike shop ready, not ride ready. If you are not comfortable building up your own bike, you'll have to take it to your LBS and that would negate much of the savings.
I'd look at used bikes over in the classifieds at SlowTwitch. There are always very nice bikes people are trading out so they can get the latest model.