Just retired my 10yr old Arai Signet GT and got a new Arai Profile Hot Rod White graphic on closeout from Competition Accessories for $299.99. I wasn't crazy about the graphics but couldn't beat the price and the long oval Arai head shape is the only one that fits me comfortably. Don't like it as well as the Signet but still a nice helmet. I've spoken with engineers I work with and they say the helmet materials wouldn't degrade in a 3- 5 yr period and it's just a ploy to sell more helmets or cover the manufacturer in the event of a lawsuit.
You paid $300 for a helmet built to the older, and less safe, Snell 2005 standard. The new 2010 Snell standard is a big improvement over the old standard since it lowers the allowable impact force to your head.