Although the ban expiration is an awesome event, the only thing about it that I'm stoked over is the hi cap mags.  Mainly because I own several Glocks.  I am thinking of purchasing an Ar15 but was wondering if it would be better to build one from the bottom up or buy something more than likely from Bushmaster???

You won't really save any money by building one yourself unless you are building something custom. If you just want a "standard" AR-15, then I'd recommend buying a complete one, unless you just want the learning experience of building one yourself.

That's what I was thinking.  I'm mainly a hunting rifle person but looking for something my wife can shoot in which she can completely disapate something.  She's not very good with my glocks so as a home defense weapon when I am at work, she has a Remington 800 with 18" barrel and folding stock.  6 rounds total.  All being birdshot so as not to go through a wall and hit our kids, but will completely dismantle an intruder.  She hates recoil though so I figured an AR15 would be perfect.