http://www.shoraipower.com/p-209-lfx36a3-bs12.aspx
This is could be the lightest DD battery for the money, open this link then click on the red more information at the bottom of the page for full details.
http://www.ballisticparts.com/produc...ies/16cell.php
This one is actually cheaper and lighter but with less CCA but you still use it as DD battery i guess