So I was gifted a forged Mega lower with a bullet upper from a good friend. For my first AR, I built the lower and bought a complete upper. I had similar plans for my second one thinking that this would be my last one for a long while.
I have basic hand tools but nothing gun specific and don't really want to spend money on specialty tools I'll probably use once.
Now I'm not sure if I should buy the parts and build the upper which is a very nice piece of metal.  Or sell the upper and add a bit of cash to buy a complete which I feel would be a dick move but  I would have a complete rifle much sooner without a box full of tools gathering dust.

Anyone been in a similar situation? Advice?

Go get a CHF/or premium PSA kit for the lower you have now.....I would keep the billet upper for a future build.  PSA kits are crazy cheap right now.  But what do I know, I shoot the PTAC stuff...

Once you buy the tools you won't use them just once, don't ask me how I know. I don't build rifles to save money. Quite the contrary, I build each rifle using a specific idea in mind using premium barrels and bolts. The other hardware is selected based on utility and style points.

The basic reason (for me) for building a rifle at home is the ability to run premium barrels like Noveske, White Oak Armament, Shilen, CLE, Rainier Arms etc. Simply buying a base level economy barrel to build a blaster is not what I do. If I wanted that I'd buy a Colt 6920 OEM and add the furniture I like instead.

I haven't purchased FMJ ammo in close to thirty years. Sierra, Nosler and Hornady match bullets are my go-to fodder and accuracy is my goal. Even rack grade rifles from Colt, LMT and FN-USA shoot those bullets with excellent results, match barrels make them shine.

I don't shoot competition, long range or anything like that. It would mainly be a range toy/HD weapon so top shelf components aren't really a concern for me.
My wife would probably kill me if I brought up the idea of buying/building a third ar. A thought I had was buying components and having a local gun smith bolt them up.

My goodness it is so easy and fun why the hell pay someone to do the fun and educational part? The fun is planning & designing your individual build then putting it together so it's no longer mysterious how it goes together. Then getting up and running!

Any damn fool can go buy a gun at the pawn shop or gun store.

Build. Tools and knowledge/experience are good investments.

Get on the home town pages and find someone close by to help. I'm sure you can find another AR fanatic close by with the tools.
Also the only special tool needed is to torque the barrel nut. Depending on you hand guard you may not need an armorers tool for it. I assemble all mine just using my mechanics tools. Take your time any it will work. Worst case is you get it all together and have to take it to a smith to torque your barrel nut and buffer tube nut.
Mike

What Mike said mostly.

If you don't have a decent bench vise, you need one for lots of things besides guns. You'll wonder how you got by without it. You can get decent armorer's wrenches, vice blocks, and a torque wrench for not much money. Select your handguard wisely, and you'll be fine. You might not even need the armorer's wrench or torque wrench, but both are useful for other things.

Harbor Freight is good enough for the vise and the torque wrench. I got a perfectly good armorer's wrench and vise block off eBay for about $30 total. You can certainly buy better, but you can get by with that stuff.

Thanks for the replies fellas.
I think I'll build it as funds allow. I do not own a vice and I have wondered in the past how easy some projects could have been if I had one, lol.
I guess it is time for research and shopping. The handguard is what would give me the most trouble.  I'm a total newb when it comes to the ar platform and have really only held one other AR but a slim mlok rail is what I think I want.
Is there a differnce between a $150 rail vs a $250+ Rail? I want to do it some justice but don't want to go broke.
Does one style or brand offer easier installation over others?

Im personally a fan of the Freedom line with melonite barrels.  AK operators union did a 5k  round review on one and it passed all of their tests. Mine has been flawless also

Buy if you're likely to resell. Build if you're a man.

I was in a similar situation not too long ago for an SBR. I bought a stripped lower from PSA and a LPK and stock kit from BCM. For the upper I was considering doing the same, but once i started looking at prices+shipping for individual pieces it came out to be more expensive to piece together.  In order to piece it together for less you would have to find a lot of great holiday deals and purchase from the EE.  A complete upper from say BCM, Ballistic Advantage, AeroPrecision, AndroCorp, MI, etc would be less expensive than piecing it together in my case.  If there is something very specific i say build it but if it is just a run of the mill gun you want buy assembled as it will be less expensive.