No, I'm talking about how volume relates to profits.
True, but your reply was to a comment concerning a subsidy.
Big stores like newegg, amazon and wal-mart move a lot of products. Therefore, they can afford to make a slimmer profit on each product sold since they sell so many.
The facts are true, but the reasoning is backwards. As it is stated above, the assumption is they move a lot of products and the consequence of such is they sell each item for a smaller profit margin. Conversely, they price items such that they make a smaller profit margin therefore they sell more products due to the law of demand.
For subsidies, I've already stated how we don't have enough info, plus see below.
We do have enough to make reasonable estimates, however. The maximum operating costs per customer is $40 per month (the price of cheapest plan available). The actual operating costs are certainly lower, but this works for the time being. How do we know they can't be more? This value represents the point at which the baseline customer provides no profit to AT&T and serves only to increase network demand (increasing costs and degrading service). The only exception would be if this service was priced as a loss leader, but for various reasons that can not be true. Now, we can figure the subsidy cost for AT&T is $200 per iPhone since that is the difference between the upgrade and non-eligible upgrade pricing. Finally, a $100+ plan is upgrade-eligible every year, so:
($100 price -$40 cost)/month * 12 months - $200 (subsidy) = $520 profit
This is the minimum profit AT&T makes over the course of this upgrade period and is over two and a half times the initial investment. Over the course of the full contract it's over six times their subsidy cost! To determine the time it takes for them to make up the cost of the subsidy,
$200 / ($60 /month) = 4 months (fractional months are invalid as payment is a step function)
Again, this is the maximum amount of time it will take to repay a subsidy when qualifying for yearly upgrades. The cheapest iPhone plan profits only half as much and will therefore take no more than 7 months to repay. Of course, these accounts are only eligible for upgrade every 18 months. Realistically, the operating cost per customer is probably somewhere in the $20-$30 range, meaning AT&T profits 3 to 4 times the subsidy before customers are upgrade eligible.