Just did the lower and got it done in under an hour by watching YouTube videos. Can I also save money by building my own upper? Or is it too much for just a guy and some tools?

If you can assemle a lower, you can assemble an upper.

Takes a few extra one time purchases or loan of tools for upper, but upper is not rocket science either. You can't change the headspace its either right or wrong, and you can't hardly go wrong following directions.

What parts do I need besides a barrel and the stripped upper

Handguard set or free float rail, depending on the setup. Front sight, gas tube, etc. Upper parts kit, if you bought a stripped upper.

Minimum tools would be:
- good strong bench vise & leather strips to pad the jaws
- barrel nut wrench
- small punch set
- hammer

Doesn't look like there's much savings in building an upper

There is the satisfaction of building your own and you will learn a lot. They tend to multiply.

If you're not looking for a generic upper, you can build the upper just the way you want.

You won't save much, but you will have exactly what you want. A name brand upper will often hold value better than one built by it's user. At least, that appears to be the way things are.

I have decided to just buy one

I do both. To get exactly what I want I am building them these days, for quick and convenient I just buy. I am wondering these days if most of the buy choices are just "ok" and not great.

I think "assembling" is a better term than building. So far all the ones I've put together, just bolted together, and shoot fine.

Compared to buying a good upper on sale at Palmetto, no, there's really not any savings, and you sometimes come out ahead buying the complete upper.

Second the comment that there's not much "building" here, just assembling. Too many people want to say they "built" an AR, when all they did was assemble parts.

Mostly depends on how particular you want to get on the barrel selection.

MM

Nailed it 100%

Yep.