Active noise reduction is not really a "must have"... but it is really nice to have. REALLY nice. Good ANR doesn't just block out sound more; it selectively reduces the most annoying and harmful sounds. Some pilots claim they're "too quiet", but the first time I used ANR, it was in the front hole of a Stearman, and it was amazing, to me, how much better I could hear the moving parts of the engine over the roar of the exhaust and the wind. and of course, with ANR, the "roar" was more like "sssshhhh".

But again, ANR is not vital; good passive noise reduction is enough just to protect your hearing. Compare specs; you may see some cheaper passive headsets that have very good noise reduction without the fancy electronics.
I'd suggest you buy a more modest set now (but try to avoid buying anything you can't wear first, to see if you like it)... that can become your backup/passenger set later, when you upgrade. Priorities should be light weight and good passive noise reduction, within your budget.
My 15-yr-old Telex headset has always worked fine, and its passive noise reduction rating is actually a little better than my new Bose ANR set (with the ANR off). It is fine for passengers, or for me if something happens to the Bose set. the main difference is that they are a lot heavier (as headsets go). I would probably have bought a lighter passive set to replace it, but I got an "insider" deal on the Bose set and couldn't resist.
Another thing to consider is finding a good
used headset... you might find a great deal on something you couldn't afford brand new. If you find such a deal online, see if you can find the same or similar model at a pilot shop and try them on first. Fit is important... everyone's head is different, and if you wear prescription glasses or sunglasses when flying, be sure to have some glasses with you when trying on headsets (or try on some new sunglasses too, LOL).
Whatever you do, don't just buy the cheapest new headset you can find... you really do "get what you pay for" with headsets.