Furuno internal battery replacement

Hey Skippers,
I'm getting a low internal battery alarm and icon on my 8 yr. old Furuno 1650 wf when turning the unit on. I've seen a few price quotes out there all around 300-350 dollars which includes saving all my info:cool:, software updates (GOOD FOR NEW CARDS ONLY) and cleaning. Wow!! All this for an 8 dollar lithium battery.
Has anyone out there had a similar issue. What was your course of action? Did you go to the furuno dealer? Split the case yourself? How was your outcome?

I think I got quoted 250-300

Rick Beck will give you good info. He's part owner of Honor Marine in San Diego.