Selling Motorbike Helmets?

Basically I have three motorbike helmets that I am no longer using and I want to get rid of them. And I know you're not supposed to sell/buy second hand helmets which is why I'm not going to sell them on eBay or anything. So I was wondering if there is like a specific website or something that would give you money for second hand motorbike clothing, cause the helmets are in excellent condition? Or would it be best if I just chucked them?