| Rich,
you might want to have a look at Nitro helmets.
They are quite noisy but a lot of it is wind coming up underneath (which I solved with a Proline wind jammer).
The quality of the fittings is rubbish compared to Arai/Shoei/etc but that's to be expected at a quarter of the price.
When I was in the States I bought a magazine (Cycle World I think) that had, in a previous edition, done an intensive test comparing helmets across all price ranges for protection. I still haven't got round to ordering the issue that the test was actually in, but all of the letters to the editor were along the lines of "congratulations for presenting an objective test that highlights high price does not equal high protection". A couple of big name manufacturers subsequently pulled their advertising as a result of the article.
Do any of our US friends have a copy of the article? | 
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