Time Trial / Time Trialling / TT

Get a cheap 2nd hand frame. And then build the bike around that with other 2nd hand bits, bits can be moved frame to frame - generally.

What I did. The frame was just a means to an ends, I needed something that fitted me (most things would given my off the shelf stature) and wasn't completely shit. I actually found something with a sweet groupset, added bonus.
I then spent the rest of my money on wheels and a saddle that doesn't make my arse hurt.

In fairness too, the first frame you get will help you understand what size frame you really want/need (stack/reach) so you'll probably get rid of it after a while for something better/better fitting, unless you're lucky and get it right first time.

So just get something that you can afford 2nd hand and don't go crazy. It wont make you faster, but use it to learn what position will make you faster.

TLDR: Hippys right, position is all that matters.

That is pretty much what I would have have said. Basically buy second hand frame and parts, and hope you can get a good position.

The only things I bought new for my TT bike were the chain, sprockets, cables, tubs, and mdcc-tester's neat Cane Creek headset cap thingy. Everything else was a combo of bought second hand or already owned.