I just replaced the battery on my 03 RG; it was the original. Should have done it earlier...I went off with the switch on last week, and after being gone less than an hour, the bike wouldn't start. Good thing I had AAA motorcycle service.
Paid $135 +tax for a new HD battery at the dealers.
On my old bike, I used to get the Sears cheapies. They'd last a year to 18 mo., but often when they went bad, they'd short out, so you couldn't even jump them to get started. Once again, you get what you pay for.