I concur with the rest. The Sightmark Photon XT is, in my opinion, the best bang for the buck. They 4.6x42 model is the one I generally recommend it's only $499, plus scope rings. The only other option would be the ATN X-Sights and they start at $599. They definitely have their pros and cons and for some people, they are a good choice, but with the little info you gave, I'd suggest a Photon XT. You can't go wrong with it, great all around digital NV scope, tried, true and Sightmark is a great company and backs their stuff up.
Night Vision, Thermal & Accessories
Pulsar, Sightmark, FLIR/Armasight, Trijicon & More