If your road trips take you to central Pennsylvania (Allentown/Reading area), East Penn/Deka has a factory outlet where sometimes they have good prices on AGM batteries (blems, etc.). It's hit or miss, though. Call ahead and they'll let you know what they have. Unfortunately when I needed new batteries they didn't have any blems in stock, although they do have regularly priced ones usually. See http://www.dekabatteries.com/default.aspx?pageid=1099
As I've posted before, for those of us on the east of the Mississippi, Sam's Club carries AGM batteries that are made by East Penn but sold under the Duracell name. I have no idea if they are the same quality as the Deka models East Penn makes, but they are pretty good prices. I replaced my two dead Lifeline batteries with three group 31 Duracell AGM batteries from Sam's @$166 each (http://www.samsclub.com/sams/duracell-a ... 3590232.ip
). Pics of the install at viewtopic.php?f=14&t=9376
The Duracell AGMs are still pretty new at Sam's, so I haven't seen any long-term reports on how they hold up. At $166 each, with an 18-month warranty, I thought they were worth trying out.