Rural King just opened here at Halls Crossroads, north of Knoxville. I bought a 2yr 6v battery for a T from them for $39.99 and they tell me that is the regular price. They also had the next group size 6v for 60 something.
I put an Interstate battery in my T 10 years ago, and it's still in there, but I probably paid more.
I like our Rural King. Great selections great prices.
Rural King does have good batteries at reasonable prices. But, Interstate is the high end battery. Don't expect any cheap group 1 battery to last.
6 Volt batteries from Batteries Plus have a full replacement 2 year warranty with no pro-rate. No other 6 volt battery I know of, including Interstate, equals that. Most have a 6 month warranty at best. I have probably bought 25 or 30 6 volt from them and have yet to have a problem. We put a new battery in every vehicle, tractor, piece of equipment, etc., we have at an auction and have had excellent luck with Batteries Plus. Their warranty transfers to the new owner which - in our experience - the other chains won't do.
I just called my local Batteries Plus store.
The Group one 6 volt batteries are $80 and the group 2 is $85.
Try NAPA. They give discounts for AAA members. My recent 6 volt was $69 plus tax with a 3 year pro rated warranty.