I've had very good luck with the group 49 battery from autozone. Its less than 70, and has a 7 year warranty as PEH said. First 2-3 years is replacement. After that its prorated. Not a bad deal, especially after reading some of the prices mentioned here!! I didn't even know anybody sold batteries with a 3 month warranty.... thats just crazy.

As far as jumpstarting goes, make sure you have good connections, let the other car idle for about 10 minutes and you should be good to go. Done this quite a bit with my 2.3L mazda pickup, and its got an itty bitty battery in it.

John
'79 300SD (2)