Where to find good batteries

So, Where is the best place to get low cost, long lasting 12v or 24v batteries? Not real concerned about amp hours or anything, i just need a good source. I have bought from a couple different EBay sellers and I am not very satisfied. I do like the Radio Shack 12v 1.5A but their prices are just too high.
Comments
-Phil
OOPS!!!! I forgot to mention the lighter the better.
I guess those are you only good options. Neither is a true 12 or 24 volt, but something close. Big Lithium ion 24 volt packs are being sold for electric bicycles.
Edit: anyone ever use this? http://www.made-in-china.com/showroom/jnmaggie/product-detailWeInHakLhBVh/China-Round-Case-E-Bike-Battery.html
Edit 2: Great, Not available in the US!!!
Battery holder (10 x 1.2V = 12V): http://www.thomasdistributing.com/10-Cell-AA-Battery-Holder_p_943.html
Charger: http://www.thomasdistributing.com/ANSMANN-ENERGY-16-BATTERY-CHARGER-Hi-Tech-Deluxe_p_278.html
I use the Ansmann batteries and the smaller version of their charger and can recommend them without reservation. Thomas Distributing is a great company to deal with, too.
-Phil