I would invest in good iron sights before buying optics. My preference in irons are these:
Rear sight: A.R.M.S.® #40™L-P
http://www.armsmounts.com/default.asp?m ... sights&id=" onclick="window.open(this.href);return false;[hsh]40L-P
I have purchased Magpul BUIS and Yankee Hill Machine flip up sights, and the A.R.M.S.® #40™L-P is head and shoulders better than either of those other two. Of course, it costs more. But, it is definitely better made, stronger, and harder......metal instead of plastic.
Front sight: A.R.M.S.® #71L-F Front Sight
http://www.armsmounts.com/default.asp?m ... sights&id=" onclick="window.open(this.href);return false;[hsh]71L-F
The front sight is pretty cheap. The rear sight borders on expensive, but in my opinion is is well worth it.
All of the better red dot sights—Aimpoint, EOTech, etc.—will serve your needs well. My carbine has an EOTech 517 on it and I like it a lot. I later added a EOTech 3X magnifier on a A.R.M.S. flip to side mount. But, if you are severely constrained by budget, I would take a hard look at the Vortex Strikefire (
http://www.vortexoptics.com/product/vor ... e-for-ar15). MSRP is $179, which is up a little bit from what I paid for my wife's ($149). They are offered with red dot, green dot, or both. My wife's has both. And they are night vision compatible. It also comes with a screw on 2X adapter, and with flip up lens covers.
The Vortex is not as robust as an EOTech, but it isn't cheesy cheap either. I wouldn't mind having one on a "throw in the back of the truck" carbine.
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