What is BB? Bottom Bracket?

Cartridge Bearing Replacement? It should be easy enough to do.

I'd start deciding what you need.
20mm vs 23mm vs something else?
28 spokes, 32 spokes, 36 spokes, something else? (your weight???)
Gravel, rough roads? Desired tire size?
9/10 speed, or do you have 11 spd in the future?


It would be an interesting project to build your own wheels, but even if you cut corners... it is hard to make a complete wheel set for less than $250.
I.E. You may get cheaper wheels buying pre-built than making them yourself. But when you do it yourself, you're more likely to add in a few upgrades here and there that you might miss on the factory wheels.