Any helmet is better than no helmet. Spend $1000.00 or $50.00. Different grades "dot" or "Snell". Snell is supposedly tougher test to pass.
I crashed many years ago with a $40.00 Woolworth special. The lid cracked in half (literally). I had a concussion for 30 minutes. People thought I was dead. Went to hospital for 2 days (met a candy striper, Yahoo!!). The helmet served it's purpose. I lived to tell this story.