Need some opinions/ advice from some of you "gun hands"

Can't say I've often if ever seen an AR in the Used rack
I wonder why that is?
At my local hardware store (note I didn't say gunstore) there is usually at least half a dozen used ARs for sale
All that's just too dang much to worry about. We have a local firearms guru that everyone in this county and several others go to......even law enforcement. Tell him what you want. He builds it. lol
It's like rebuilding an engine
Sure, you can go with blueprint and get one that will do exactly what it needs to, and comes with a warranty, but some people want to be able to lift the hood and say "I build that"