I would rather build something nicer but I have absolutely no idea what I'm doing when it comes to what I need and what's good. I have never done a build and the amount of options is kinda overwhelming which is why I was considering a complete kit.
If you have any mechanical aptitude at all, I wouldn't sweat it too much. Researching and choosing parts is unquestionably the most fun part of building an AR! There are lots of sites out there that will tell you everything you need.
Get a gunsmithing toolkit with a set of punches! I have this and am happy with it:
Weaver Deluxe Gunsmithing Tool Kit WV849719 849719
An upper receiver vice block is another good, cheap tool to have.
You'll also need an armorers wrench. Not sure if he's still here but there was a guy selling them in members classifieds, I believe. I have been VERY satisfied with what I got from him.
For uppers I have no input. I have had quentin lowers (from group buys here) so I used quentin uppers. No problems with them at all but I'm sure there are many good ones.
For the Lower Parts Kit (LPK) you definitely don't need to go crazy. You can upgrade the trigger later on and blingy selectors and bolt releases don't do anything. Did I use blingy parts on my ludicrously expensive SPR build? Yes, yes I did...but they don't do anything different. I used a Spikes enhanced LPK on the first AR I built for my father and it worked out very well. If you really want to go cheap, the regular Spikes kit should be fine.
For the bolt and bolt carrier, get the M16 cut but you don't need any fancy coatings. I have coated failzero stuff on my ARs but I actually run a bolt I ordered with the barrel (supposedly "matched") on my SPR in the coated carrier. Haven't noticed any difference in cleaning. Maybe the coatings would help in adverse conditions...we'll find out if my ARs ever actually see adverse conditions.
Barrel is probably a good place to spend money. I would do a 16" for a first rifle. I did a 16 on that first AR for my old man. My SPR has a 17.9" Compass Lake barrel on a Douglas blank, for authenticity's sake, and my shorty is a 14.5" Daniel Defense with pinned welded brake for legality's sake. I'm quite happy with the DD. I will probably build another upper with a 16" barrel at some point. 16" or shorter seems to me to be a good length if you plan on shooting from a standing position a lot. If you want to bench rest then go for whatever you want.
For the gas block make sure you get the right size for the barrel. Set screw is probably easiest. Can't go wrong buying a block from the same company that made the barrel, eh? You don't need an adjustable gas block.
Gas tube, make sure the length matches the barrel. Otherwise, who cares.
Brake, stock and forearm are all up to you, get creative. I have PRI forearms on my rifles and I LOVE them. Nice smooth grip where your hand wants to go and rails only in the places where you need them. I've never seen anyone using PRI except other SPR clone builders on the internet. No idea why because they are awesome. I used a Quentin Defense keymod one on my fathers AR, which was a mistake. Stick with standard rails. I may go with some other fancy-pants forearm on my next AR purely to look cool, but the PRIs are just so damn good.
I've only recently discovered the crazy stuff people do with cerakote, so I might even just use another PRI and have it coated to make it more fancypants.
If by preban you mean pre-94, the world is your oyster for stocks. If you mean pre-7/20, then you could certainly go with a fixed stock so you don't have to deal with pinning it or getting it pinned. That said, you have to swing by the gunsmith to get your brake pinned anyway, so might as well just go for it.
