Generation does in fact matter a great deal if you're trying to go to 200 yards. Gen I won't be useable at 100 yards unless it's a very bright night. I'm not even sure if a gen II device would useable at that distance (without a light source, that is)... maybe in very open terrain with no grass/weeds. Generation III is out of the question as it's not available for twice your price limit.
Actually, I think my advice with your price range is to go with an IR source light and a solid gen I scope. When I say IR source light I'm not talking about the little flashlight thingy on the riflescope. You will need a seperate spotlight with an IR filter lens. That will keep you within your budget and be useable (a hassle, but you can develope techniques to overcome it). You can find an IR blackout lens and spotlight for around 100 bucks, and I have seen gen I scopes for around 400 or 500 dollars on optics planet. This would be really the only way I could see you getting a 200 yard hit at night for under 1k.
BTW, with night vision devices, generally less magnification is better.
