I have built 4 computers. 2 for myself and 2 for friends.
In the case of me building mine, I purchase in pieces. The most recent one started with the case, motherboard, ssd, cheap ram, psu, cpu, and finally the graphics card. I intend to put another ssd and a storage drive in it, expensive ram, etc. Oh, yeah, I also got a 3 120mm fan liquid cooler for the cpu and the peripherals. Took about 6 months to build so I could run it.