Marine parts, but why not...
2 Optima Deep Cycle marine batteries, work fine in a car. Have had one in mine for 6mos. As for all of the "If it goes dead once it is garbage" claims, you cannot use a basic garage charger, need to throw 50 or so amps at it. (That is what they told me this morning)
They were in a boat for 10mos, and in use on the water for a few weekends over 3 mos last summer.
$75 each
Also have a Dana Marine red billet battery box, looks nice.
Retail is around 160, also asking 75.
http://img.photobucket.com/albums/v177/Hyperbaja/P1010293.jpg
http://img.photobucket.com/albums/v177/Hyperbaja/P1010294.jpg
http://img.photobucket.com/albums/v177/Hyperbaja/P1010295.jpg