No, I'll figure out what parts I want, order them with the best deals I can find, and put them together in a case.
that was exactly how mine was built with a cheap motherboard, a case, a hard drive, a disc drive, a WIFI card and some decent amount of RAM. and 2 fans and power supply also
I installed a sound card myself, I agree that you need to know where everything goes inside the case to be successful at do it yourself kits.
the key word I guess for building would be. To be gentle and don't force or bend anything inside your computer
(edit) and don't forget an operating system like windows 10 for example without an operating system your PC would be worthless, it usually cost at least $150USD if you don't already get an OS with with your kit. or bare bones building one. and you will also need a monitor or a flat screen tv and speakers for sound
And a keyboard and mouse is required but they should be vary cheap to obtain new or even cheaper used