Is there a generic version of the battery for this car which might be cheaper than the dealer's?

Try PEP Boys. I think they have one that is a generic brand. I have found the dealer price is way too high also.

I know!!!! Last winter my battery partially froze (and she still started and drove) and my dealer recommended I change it....to the tune of $275 Canadian. Ouch!!!! I have not changed it yet but I will before this winter. If you live in Canada try Canadian Tire. They might have one cheaper.

Make sure the replacment battery has a vent tube on it same as the original as the battery is inside the cabin and must be vented to the outside.

I replaced my battery in Florida last winter only because it was 7 years old. Tried walmart but they don't stock them because they said they were to difficult to change. Went to napa. battery #7578. Same as original [770 amps] except the vents where in the center of the ends instead of on the sides of the ends. The vent hoses went under the cables & were long enough. The battery was $87.00 plus core deposit which was returned when I took the old one in. This compared to about $140.00 for the battery called for in an 03 Lesabre. Thanks to the knowledgeable counter person. Norm

Mills Fleet Farm battery #7872 Group 78, 1020 CCA at 32 degrees, 850 CCA at 0 degrees, externally vented for installation under the rear seat, three year free replacement, additional two years pro-rated .........$84.99 everyday.