-There are different configurations of the 4x5 interlocking plastic holders that many of us use, including 1x1, 2x1, 3x1, 4x10, etc. They snap together, so you can build your pack from there. Price on those are generally $.10-.15/cell.
-The
largest ammo box I found on Luna Cycle can fit 4
shark packs. That's theoretically 2.8 kWh capacity. Depending on what you have, you might want to simply build your own.
-I haven't looked into the offset config like you linked to, but I'm fairly certain that I've seen them specifically marketed to e-bikes/scooters/other mobile applications. Price on those are most assuredly going to be a bit more than your standard 4x5.
-What wattage are you planning? That will drive your busbar and fuse wire/metal strip selection.
Here's a link to ampacity of metal strips, for reference.
-I'd love to see the motor and controlleryou've selected/are planning. I have a kart that I'm considering elektrifying.