I bought my helmet mirror from Chuck Harris. (I don't like helmet mirrors very much except when commuting in traffic or touring in the city. I've actually had a vine from a tree in the park hook my mirror and almost yank my helmet off.
I still use the one I bought. It took a little getting used to. Yes, it is valuable when changing lanes.
Here is some info: CHUCK HARRIS MIRROR
The one and only Ultralight Chuck Harris mirror. Handmade especially by Chuck for the SCBC. The SCBC emblem appears on the reverse side of the mirror. Helmet style or temple style (attaches to glasses - narrow and wide temple styles available). Various colors. Once you try a Chuck Harris mirror, you'll never use anything else!
PRICE: Contact Elaine (jsnively@sssnet.com)