<I agree completely, a helmet is not something I would try to buy online, without trying on. Unfortunately where I live if it doesn't run on kerosene you can't buy it here, so I'm going to have to travel to find one. Can anyone recommend a good helmet retailer in the St. Louis area? I'm close to there, and going that way in the next couple of weeks.>
I had the same mindset. I ordered the Lazer Monaco from Revzilla following their guidance. Fits perfectly - and a great helmet. They will allow you to return it - at their expense - to resize or for a refund if you don't like it. Mine fit on the first try. I would buy from them again.
Chris