Don't get a used helmet. Recommendations are impossible, it's all about how it fits your head.
Go to a store with a wide selection and have someone help you find the right fit. People tend to buy a helmet that's way too big.
I have a Bell Vortex ($200) and an Icon Alliance ($180), both of which are made for longer oval heads like mine. If you find a Bell that fits get the photochromic shield to go with it, it's awesome.
The Vortex is nice for night riding since the photochromic shield becomes 100% clear. The Daft Punk gold shield on my Icon is almost unusable at night.
I'm looking to get an Arai to take to the track next year, this exact one: