Re: Whats a Good Entry Level AR Scope
I completely agree with many of the above responses.
Primary Arms has best bang for your buck combo red dot with mount.
Vortex is going to have great options for relatively inexpensive optics that function well on AR's (i've owned the PST 1-4x and 4-16x on two different AR's; happy customer!)
However, I also agree with the "buy once-cry once" statement. If you want something to last a while, both battery and product life, consider something like the aimpoint PRO. I put one on my SBR, couldn't be happier after switching from my Eotech 512.