You can get by with a crappy gen 1 hunting rifle scope, but that is all it will really ever be these days... A gen 1 crappy scope. If you have nothing I would say it's a step up depending on what your current role is at games.
You could go right to thermal for $1000 here:
Which would give you a nice field advantage vs a gen1 nvd.
For any head mounted nvd and full seal I use smith optic low profile goggles, they are typically easier to obtain vs ESS now and seem to do the same job. These are handy if you're doing a lot of cqb and are concerned about taking a bb to the corner of your eye.