If you're looking to save some money, and don't need the latest Snell SA2010 rating on a helmet, then take a look at some of the Snell SA2005 rated helmets on closeout at SoloRacer.com...
Save $300... Pyrotect Carbon Fiber helmet w/Flame Graphics
Save $250... HJC SI-12 Carbon/Kevlar
Save $200... Zamp RZ-31 Solid White
Save $200... Zamp RZ-31 Blue Graphics
You can see all of the Snell SA2005 closeout helmets over at SoloRacer.com. These are only available while supplies last, and quantities are very limited.