Having a bike made & want to start collecting items

[Bluetree]

I recommend going to a fitter before building up a new frame. If they have a FitCycle, or equivalent, it can tell you exactly the size components you need. They can dial in your new frame's exact geometry, and measure your needs according to a fit, or by taking measurements off your existing bike.

When I built up my last frame, I assumed I needed the same size stem as my last one, but because of the different geometry and setback, it turned out I needed a longer one... a mistake that could have cost $100+ since I was buying a lot of stuff on eBay.

Your intentions also have to be considered when choosing components. Do you prefer aero, or lightweight? Race, climb, touring or all-purpose? If you climb alot, you'll want to consider spending a bit more for lighter, more expensive carbon parts. If you want to race, perhaps your greatest emphasis should be on a wheelset. Do you want clinchers, tubulars, or tubeless... Each has aspects of ease vs performance.

Also keep in mind the Golden Rule of bikes:
Lightweight. Strong. Inexpensive.... Pick two.

Enjoy yourself in this process... Bike building is fun!