$50 makes you smarter than those that ride without protection at all, but a good $100-$200 investment in a reputable helmet is money well spent. Lightness could make all the difference when it comes to neck trauma, but I don't see many other advantages in my $400 Shoei Multitec and my $600 UVEX carbon fiber over a midline HJC or other brands in the $200 price range. The important thing is avoiding polycarbonates, they bounce when you hit the ground, not a good thing. Advanced compounds like fiberglass and carbon composites absorb the impact, which reduces neck injuries. We used to have a bunch of helmets cut in half at the old shop I worked in, there was a huge difference in the shell construction of sub $100 helmets vs the more expensive stuff. Impact ratings do not reflect the helmets ability to absorb shock, that is why a well made helmet needs to be disposed of after a hard hit. As others have mentioned, it all starts with proper fit.

Cheers!
ChinaV