https://helmet.beam.vt.edu/bicycle-helmet-ratings.html
2 best helmet is $100 from Specialized.
Interestingly, in the top-10 or so, the road helmets are all more expensive than similar protective mountain helmets. There are a few <$100 road helmets, but they’re mostly in the $250-$300 range, while the mountain helmets are all sub-$200.