Helmets is the same as boots: Just try them. I bought a Red Trace II, just because it fits the best to me. The most expensive helmet fit the worst to me, so it's not about price. The higher the price, the lighter the helmet, but I don't know what that 0,2 kilograms (0,4 pounds I think) really matter on your head which weights 20 times that difference!
I just bought my first helmet, Smith hustle. I paid $50 following a link in another thread on here. Nice helmet that is audio compatible.
My son has a protec helmet with audio and it has served him well for 2 years. I got my niece a red helmet. She got a concussion while wearing it and doesn't remember anything but waking in the hospital. From the stories the instructor and other campers tell she is lucky to have lived. Took a 30' jump then Wiped out going about 50mph after catching an edge. She hit some hard surface along the edge of the trail at hood in summer. Her helmet is lighter than the protec. My Smith is about the same weight but mines an XL and hers a Med.