I have a Shoei RJ Air open face helmet. It is DOT and Snell M2000 rated. I tried one at a local dealer (they were not very customer oriented when I was looking at bikes last year so I didn't feel too bad when) I ordered it from
http://www.helmetcity.com/ It is quiet comfortable but a little loud when I open the air vents for flow through cooling - at least I am not familiar with the sound of wind rushing THROUGH my helmet. It was $198 delivered. About $40 less than getting it locally.
I must compliment helmetcity for their service. I ordered it on a Monday about lunchtime, went and fetched my new '06 S40 with my truck, put it in the garage. The helmet arrived at lunch time Wednesday in the Big Brown truck. I had asked them if they had any faster shipping than the free standard 3 day. The sales lady determined that she could send it UPS ground from TN to NC in 2 days and it would cost less than 3 day air shipment.
Ken
p.s. in the old days it was easier - if you wanted a good helmet you went down to your local dealer and purchased a Bell - period. It you had a $20 head you purchased something at K-mart. There are a lot of choices out there today although none made in the USA that I can find. Proection and comfort are the keys. Try before you buy.