Nikon
Bg, Soem great idea's here, I have heard about a number of guys using the MONARCH African on their AR. Never a complaint and I think the logo is pretty darn cool anyway!
A few question's you need to ask yourself are, How far do I want to shoot this rifle? Will I only be shooting at paper target's or reactive target's at different distances as well? Do I want to predator hunt and again, distance comes into play, how far might my shot's be, will they have to be quick because of the terrain/brush? YOu have the first question down, price. I know we can find something that will work for you. If you are staying inside of 200 yards, the MONARCH 1-4 Point Blank Reticle can be found in your price range. The P-223 3-9 BDC 600 will let you reach out and touch about anything you want. Especially when you use Nikon's Spot On Ballistic Program to really dial in your scope,rifle and ammo.
If you have more question's please feel free to drop me a note. Many of the guy's here can also give you some great info especially about what worked for them and why.