If your filter is not too dirty you can blow it clean with compressed air. Just keep the pressure low enough so you don't blow a hole in it. Apply the air to the side that has the wire mesh on it.
Bike Bandit sells a replacement that's way less than $40.
http://www.bikebandit.com/hiflofiltro-air-filter?m=147605The one I linked to fits a 2006, but I think they are all the same.