Even the *darkest dark* Gen 2 and Gen 3's need IR/Light Source, just not as much as Gen 1 I guess...
The biggest difference imo between Gen 2's would be light gain and resolution (usually much worse than even Gen 1's, but it makes up for it in other things) though...
I personally got a D300 MS for $1515 after duties, taxes, shipping, and insurance from the states, which might be a good option? (A bit heavy, and I guess I would prefer better resolution, but the D300 HP is around $1000 more, so up to you)
Basically you should have 400-500 left though to buy helmet, and mounts...
Just enough for cheap USGI mount system $100-$200, and then $200-$300 left to invest in your helmet/batteries/sacrificial lenses/counterweights/storage system on your gear for the NVG/IR Lights/IR Lasers/IR Illuminators as well as shipping costs
.
Otherwise those nice Wilcox mounting systems will run you around $400-$600 alone, and if you can even find someone selling them outside of the US.