When someone says "I want to but why spend the $$$ for only a couple of events a year" is really saying "I don't really want to that bad". Saying "I'd rather buy modern gear so I can play every weekend" is, to me, saying "I just want to get some trigger time in whether I'm uber MOLLE Multicam'd out or wearing a Hawaiin shirt."
Granted, some themes like PTO or Eastern Front are harder to find but they are out there.
Doing WW2/ historic is not about kill count, its a time machine. If you really want to do it, do it. There are few events because people don't take the first step. Trust me, once you do it you're hooked
I spent about $700 on my gear for Jump to Destiny (plus another $250 for car rental and beer). Expensive to some, though I did buy a lot of things I didn't really need but wanted. The experience was.... breathtaking, exhilarating and downright frightening all at the same time! Honestly, it made every airsoft event I've seen seem like kickball during school recess.
As stated above, if money is a consideration there are ways around that. Lots of items can be modded or substituted for a passable impression.