Microshift do a range of bar end shifters from 9 to 12 speed. The 12 speed are only compatible with either Shimano or SRAM MTB RDs. You can get 9,10 and 11 speed shifters compatible with Shimano Road (which means Shimano, Microshift and some Sensah RDs).
10 years ago when I raced TTs, my TT bike need repairs, instead of stripping the 10 speed DA group set off it, I used a 2x10 Microshift groupset on a spare road frame, and raced that for a season. The Microshift groupset was a light as DA and I found as reliable to use.
So as long as you are happy with mechanical shifting, you can get a cheap, reliable and light shifting set up.
Brakes, hydraulic TRPs TT HD-T910 will set you back 600AUD or so. Rim brakes are far cheaper, lighter and more aero and would be my choice depending on frame options.