^^^ You can get a basic snowobarding helmet for $40...
Smith Hustle Silver Max 2011 Helmet Medium | eBay
I think my helmet was about $90 on sale. Light, closeable vents so good for a wide range of temps, ratchet strap adjustment for good fit.
I've busted shoulders, ribs, wrists, and bruised my tailbone really bad over the years of boarding. I forgot how to talk and gave myself headaches for a while after hitting my head. Not really looking to become a vegetable any time soon.