I know nothing about them but my brother just called me and asked my help.
He wants to buy a NV rifle scope for varmint control at his rural homes in MN & MO at ranges from perhaps 50 to 100 yards.
Is it possible to get some sort of NV rifle scope between a $400 to $600 price point that would be decent enough to fill that bill, or is that out of the question?
I wish I could offer more input but I honestly know absolutely nothing about what questions to even ask.... 

Hi AZ.
Welcome!

Perhaps something in the PS-22 flavor is something he can work around budget wise?
It will likely have to be a used gen 2+ unit, but those can be had for around $1,000 +/-

There's also digital NVG clip ons by companies like pulsar that perhaps are an option also.
Someone will be along to provide actual assistance, but that budget is hard to work with.

A Sightmark photon and an IR Illuminator  is what you seek.

This looks exactly like something he can work with.
Actually for the price, some Youtube videos with the UNV 20IR illuminator look quite impressive to clueless me...
Thanks. 

Yes, if you are not worried about using IR, then there are some options to be had for that budget!

Yeah - as long as the hogs and 'yotes aren't going to be wearing goggles he's fine using an illuminator.