8s6p 25.2v 36ah 907wh Lifepo4 Battery 32700 Cells - $66/kWh

These batteries are perfectly balanced and come with all the balance wires so you can easily add your own BMS. You can also series connect 2 of these to make a 48v 16s battery. They were recovered from larger battery packs. Not capacity but we checked to make sure they are balanced.

Weight: 16 lbs 4 ounces.
Dimensions: 11" x 8.25" x 3"

You can also reuse the cell holders and recover the 48x 3.2v 6000mah 32700 cells for another project.