I can see the point in wanting to build. I have done many myself, but sometimes I want to keep it as simple as possible and keep the cost down while still getting a good quality AR. The one below is a recent build (sort of) of mine.
I wanted to go with the MAGPUL MOE theme, so I started to look around and find some good deals. I found a PSA "blem" lower assembly ($159) with the MOE furniture to start with. I then began to source a barrel, upper, and associated items for build an upper assembly. I was also searching the Equipment Exchange on ARFCOM for used upper assemblies. I eventually came across a guy who had a Colt LE6920 MOE upper for sale. It even came with a BCM Gunfighter CH. Needless to say, I bought it ($540 shipped). Next, I needed an optic and I knew that I wanted a VORTEX Strikefire. After checking prices on various sights, I got one from PSA for $99.99. After shipping and transfer fee on the lower, I have a total of $860 in the whole thing.
When it comes to a parts list, it is hard to make one up because there are so many various ways to build up an AR. One needs to determine what kind of look they want in addition to its purpose. For a home defense AR, I would keep it as simple as possible. The one I have pictured above is a good example. You may want to add a weaponlight of some sort for poor lighted conditions. Other than that you just need the following:
lower receiver (stripped)
lower parts kit
buffer tube assembly (mil-spec is preferred)
carbine stock (mil-spec)
upper receiver (complete)
Delta ring assembly
barrel - 16" chambered for 5.56 NATO, chrome lined, 1/7 or 1/9 twist rate, MP tested, A2 FSB
Handguards or some type
Rear flip-up sight
Red Dot optic (Aimpoint PRO, Primary Arms Classic, VORTEX Strikefire or Strikefire II, VORTEX SPARC or SPARC II).
Magazines - PMAGs are favored (at least 6 of them)
Ammo - 5.56 NATO (5.56x45mm), Federal XM193 55gr., American Eagle 5.56x45mm NATO 55gr., Independence 5.56 NATO 55gr., Federal M855 62gr., American Eagle 5.56 NATO 62gr.
This should be a good list to get started. A lot of homework is due. There is a lot of research that goes into looking up parts and accessories.