AR build

Im building another AR since the Colt is starting to show some age and I'd really like to keep it as nice as possible for my kid(s) to enjoy as much as i did, and i was wondering if anyone could help me out.

Im trying to build another 20 inch HBAR model, and i was wondering where the best place would be to buy an upper? Im done with the tacticool stage and im just looking for a fixed carry handle upper.

I had an olympic arms guy living by me i was buddies with who i could get parts from, but he has since moved to texas so i lost that help...

So any advice or links would be appreciated.