When I was looking for a deep cycle/trolling motor battery a
couple of years ago, I found that Costco did have the best price
for one of the highest capacity batteries. Further research and
I found that Costco's 'Kirkland Signature' batteries were made
by Johnson Controls which makes such obscure names as "Diehard,
Duralast, Energizer, Equalizer, Eveready, Everstart, Interstate,
Motocraft, Optima, and Prostart'. :^)

You can find this info at:
http://www.johnsoncontrols.com/bg/Pr...?section=brand


-Jim