Im just guessing here, but... The XS power stocking dealer is going to get the Batteries cheaper than Joe the ragman off the street, Hence the "$1500 buy in".
And im guessing XS power is not going to ship the Batteries UPS/FEDEX as they would to us, they are probably going to use a Fright company.
So cheaper batteries, cheaper shipping, will allow the dealer to compete with online prices and still make a profit.
Ive run Large group buys in the past. When you get a group together spending $15k+ it lets you get Distributor Pricing and you get cheaper shipping when its on a pallet on a 18 wheeler.