After my first PC purchased in the early 90's (386DX-25 with 4MB of memory and a 105MB hard drive), I built all my personal desktops. I don't think I saved anything building them myself because any potential savings was spent on higher quality components and some case mods (back when that was "cool"). Depending on the machine, the components may have come from the Computer Shopper, Fry's, Comp USA, online, or the random local shop. Spending hours assembling all the parts, wire wrapping, and using zip ties to hide cables was half the fun of getting a new machine. For better or worse I doubt I'll ever do that again. I've moved to laptops for my primary machine with a good sized NAS appliance in the basement for redundant storage. Just don't see the need for a big machine taking up all that space under my desk anymore.
For my parents or non-computer friends (depending on the era), I always recommended a Gateway, or Dell. I'd help them spec it out on the website, but having them go for one of those relieved me of tech support duties for the hardware at least.
Old Hand, I used to often build my own when it was a challenge, as you mention, instead of a nuisance. But when I focused on databases, I got away from spending time on hardware. I also use the large NAS storage, but don't have it in the basement. I have considered putting it across the street in my son's house though. I could do backups easily enough as we do have access to his wireless too. Off-premises storage would add some safety. I do have three desktops in my home office, but really should get rid of them as two of them are obsolete.
All my active work is done on my 17" laptop that actually is almost never moved from front and center. We don't worry about space because we have a large modular furniture system around three sides of the office, with 5 screens on the work surface, and can roll from one machine to another easily. Our only space constraint is that there are two lateral files under the work surfaces which to sort of get in the way. We have eliminated lots of files by electronic document storage but still can't get away from some. This is the main reason for needing off-site storage, but I will never commit my data to online storage.
We used Gateways, HPs and Dells for many years, but our newer machines are Asus and Samsung. I love the honkin' Asus ROG laptop for my database work and my wife uses her Dell for her graphics software. My Asus ROG will update 1.3 million rows in a SQL Server database in about 13 seconds, which I don't think is too bad, but I have some batch DB processes that will run for a couple hours what with SSIS packages and SQL stored procedures.
Disaster Recovery = Backup ( Backup ( Your Backup ) )