Nikon makes a great scope and can be bought for very reasonable prices. Vortex scopes are real nice and competitively priced for their feature sets. A lesser known brand but one that is great is Sightron.
Others to look at are Bushnell, Millett, leupold, and Zeiss. Zeiss will be at the top end of your price range in their lower end scopes though. Maybe slightly over $600.
Last edited by ripnbst; November 11, 2012 at 02:10 PM.