Just search "group buy" here on ES, and you'll find a lot of reasons why many (maybe most) people here would not do it, and would discourage anyone else from doing it. As good as the idea is, it requires that
A) everyone involved be honest and pay up, and the organizer buy and ship everything on schedule and at the prices promised. That's sometimes a lot of people to expect to do right, and a whole lot of work for the organizer and reshipper to do, for which they probably arent' going to get any compensation (if they do, the cost per person goes up, probably way up). It only takes one person in the group to screw up the whole thing for everyone.
B) that nothing changes from the time it's organized and payment collected, to the time things get shipped out. Many things can change or go wrong: Costs of items could go up after money was collected, but not yet paid to vendor, or even after vendor was paid they could change their prices and not honor the original deal. Cost of shipping could go up, or be delayed for months, either by vendor or shipping company, and that could happen either at the original shipping time from vendor, or anytime after organizer gets the stuff and starts to ship it out to individuals. Shipping rules could change, and disallow shipping of the items purchased, or make it exorbitantly expensive.
C) Presently, shipping rules may well already be in place everywhere preventing individuals from shipping these batteries around anyway.
Might just be my perception filters, but more often than not, previous GBs here on ES seem to go very wrong, for any or all of the above reasons.