I'm new to building PC's from scratch too, but based on my math and calculations on several pre-built units, you don't get to maximize price and performance, as they often skimp on things that are important such as MOBO quality, PSU quality, storage...
Your hesitance seems to be spawning a lot from not being very confident in building a PC yourself, and my advice is to watch a ton of videos on Youtube building rigs, make your own checklist of a great process, and to make sure you don't overlook the details. I think I have watched over 20 hours of videos online, read hundreds upon hundreds of posts, and this was even before I wanted to build a PC. Not that this qualifies me to build PCs any time I want, but as a fellow newbie I think doing this will give you a very healthy idea of how to proceed once you have the components in hand. I know how I want to build my PC, what precautions to take (anti-static issues, assembly to fit the case, etc.) and most importantly I will save HUNDREDS building it myself giving the most bang for your buck.