500-1000 is still in the range of Gen 1. Gen 1 units are often useless unless accompanied by an IR Illuminator. Even then the range, picture clarity, and usefulness of the device will be limited and have you questioning your investment.
If you look around, you can get a really good deal on a Gen 2 unit at time, or even some Gen 2+ Units which preform almost as well as US Gen 3. These range from 1500 to 2000 for a decent Gen 2. For one of those really good Gen 2+ units, you will be paying 2500-4000, or possibly higher... But you'd be crazy to break that price mark.