300 yards is a long way in the dark. Anything in the $500-1000 range is going to be a modified digital camera CMOS and likely be fixed magnification with optical zoom. For adequate target identification at 300 yards in the dark, the budget digital stuff just isn't going to cut it. Will be hard to tell the difference between a coyote or the neighbors dog. On top of that, the digital stuff kinda sucks at gathering ambient light so you'd need a pretty strong IR Illuminator to even reach 300 yards. You might be able to get away with one of those ATN X-Sight units and spend the remaining budget on a powerful illuminator but in your mind you'll know it's a compromise and you'll wish you'd just saved that $1k and put it towards the real nightvision setup. You can get a good PVS-14 for less than $2500 and then outfit the rifle with an IR laser for $500 and you're good out to 200 yards using just the laser for targeting.

This is one of the arenas where "buy once, cry once" is actually good advice. I have a couple digital nightvision scopes as well as a PVS-14 and both have their uses. The digital stuff is fine for picking off racoons or dillos at 50 yards with a 22 but taking care of larger nuisances like wild pigs and coyotes is where the actual nightvision and laser targeting is the better solution.