There's a seller on eBay, "jennypenney1" who told me a while ago that they'd have the newest helmet just as soon as it was released. You can pick your size and facemask as well but I think it's an upcharge to do so. I bought a Sherrill-era white helmet from another seller on eBay under much the same conditions five or six years ago.
I don't think one will be hard to find one once they're available.