Having played with gen1 I can honestly say that you're better off with your eyes 99% of the time. That pvs14-alike on aliexpress is actually a small tv camera hooked up to some fairly shonky plastic lenses and a large array of IR LEDs, a guy on UKAZ had one and he claimed the field of view was about 10 degrees and it was about 1.5x magnified.
A proper set of gen1 (with an actual intensifier tube) will set you back a few hundred quid, but you're genuinely better off with your eyes and a half decent torch.
For a gen2 monocular you're looking at £1,000+ and while they're usable, you can pick up a second hand gen3 monocular for £1,500 ish.
From bitter experience i can say that with night vision kit it's very much a case of buy nice or buy twice.