If you feel the urge to go down that rabbit hole, why not?
I've assembled several uppers and lowers now. It get's a bit addictive (fair warning)….grin
I put in basic mil spec lower parts myself, and that's just my personal preference. Mostly stripped lowers from PSA, and AR-Stoner lower parts kits from Midway.
Uppers seem simpler to me, less small parts overall. I usually use uppers from AR Stoner and BCG's from AR Stoner or PSA.
You can generally spend as little or as much as you want/need to find your AR happiness.
FYI
All of PSA's uppers and lowers are manufactured by Spikes Tactical
