Try Wal-mart. If that doesn't work use your local Yellow Pages and try calling your local automotive parts stores. Many major automotive parts stores carry a certain amount of motorcycle tune-up parts including batteries. You might be able to find one for less than the dealer battery.
But remember that if you go cheap you will get cheap. You may not be very satisfied when your cheap battery leaves you stranded.
Kind of makes one wonder where else you are skimping on your motorcycle care. If you can't afford to properly maintain your bike maybe it is time to put a For Sale sign on it.
