I bought one of these: https://www.simpsonraceproducts.com/products/simpson-desert-devil-racing-helmet a couple weeks ago. I also had Simpson fit the quick release HANS anchors on it: https://www.simpsonraceproducts.com/products/quick-click-anchor
When I tried it on, it was way too tight and almost painful to wear. I ordered a replacement that is one size larger. From my research, this is one of the cheapest helmets with built in comms that is easily adapted to the Catalyst.
If my new helmet doesn't arrive before December StarCar, it will have been used once. Otherwise it's brand new and has never been used.
Price is negotiable, it cost me $738. SA2015 spec.