Auto-X helmet question

[j.fro]

I'm planning to do about 6 Autocrosses this year, and I'm trying to figure out what I need in the way of a helmet. I've read the PCA club racing rules and seen all of those requirements, but I'm not planning on doing anything that serious. Do I need to lay out $400+ on the latest Snell rated bucket, or can I get away with a DOT helmet for less than half that cost? I'd love to know what other folks are using and where purchases were made.