RRA is a great retailer. (Or so I've heard)
http://www.rockriverarms.com/You can call them and order your AR however you want. They list the basic parts(left side navigation) as well if you are interested in building one yourself. I wish I would have built mine.
If you want your AR for ranges 0-50 yards, get a red dot. EOtech, burris, or aimpoint all make good models. I got my red dot at On Target when I purchased my AR. This is the one I picked up used $110. It's ok, nothing fancy.
http://www.burrisoptics.com/xts135.htmlThe rifle I picked up is the Remington R-15 with collapsible stock and 16" barrel. It's more of a predator rifle but I put a lot of rounds through it.
For a longer range rifle(and I mean LONG RANGE), I have the Remington 700 XCR TLR in a .300 Win Mag.
http://www.remington.com/products/firearms/tactical/centerfire-tactical/model-70...The scope is a cheaper $300 model which I want to upgrade but I haven't shot past 250 yards yet. Not sure if I need to.
An AR-15 will shoot 250 yards easy with the proper optics. Oh and with the carry handle thing you're talking about, you can carry a gun by it's scope if you get good solid rings for it. It'll be fine.