Walmart!

I've never had a Wally batt go bad before 5 years. The one in my '84 D100 is 7 YO. The one in my '00 Neon is 4 YO and the one I had in it before went 6 years (OEM went 5).

Some last even longer.
The one in my '68 V200 is over 13 years old, still cranked it up last week and the one in my '68 V100 has one that's 11 YO.

And if they do bad bad early, there's always a Wally nearby that is open 24/7 for a warranty exchange.