Get a ballistic helmet, if you cant afford or find one, get a motorcycle helmet or even a construction hardhat. The airsoft larp gear will just get you hurt.
Also, and this goes for ballistic plates too, if it ain't NIJ certified it is worthless and will get you killed or injured.
https://www.hardheadveterans.com/blogs/reviews/bulletproof-helmets-what-you-need-to-know
https://www.midwayusa.com/product/1017316264?pid=474609
It's hardly ideal but you can sometimes get ancient steel pots for cheap. Just do some research to make sure you're getting a size that fits.
https://www.midwayusa.com/product/1020784651?pid=123892
Surplus shows up sometimes, too. I have no idea how quality it is, but...