Ironworker ,
How good a scope do you want on your ar ? I have always been a of the mindset that says buy the best you can afford . You will not be dissapointed so easily that way .H
What do they cost ? I would recommend the nikon buckmaster line as I have purchase 3 of them for different family members as gifts . They have a parallax adjustment ( a necessity imo ) and track perzact !
I reckon it boils down to how serious you are about what youre trying to do .
Jim B