Is this correct? You (The LDS) could not purchase the SP or AL product at a cost that was lower than what was sold retail on the internet? If this is the case then there must be tiered pricing for dealers and the online dealers must have huge buying power of that SP or AL product.
I don't know how much of a factor it is in this field, but I have to assume that it's not unlike others where it's not always a matter of quantity discounts. There can be offers to include some quantity of other product free or very cheap. Buy three camera bodies that retail for $400, get $50 bags free, for instance. The bags have a huge wholesale markup. Good profit for the wholesaler, BUT he won't sell them, anyway, unless the shop sells some bodies. For the shop, by selling the freebees at total profit, effectively, all that cash comes off the main product cost. There's usually some relationship between the two, so that the freebee one is something you're likely to sell along with the main because you can offer it cheap.
And there's also a matter of how aggressively your sales rep goes to bat for you, which he naturally does more vigorously when you're a good account. And, of course, if wholesale price of something happens to rise, and you're a big retailer who stocks a bunch of everything, you go for a while selling products you bought low, while the small stores sell product they bought higher. And, along the same line, since you stock a lot of everything, you go on for a good while being able to offer discontinued and cheaper (but perfectly fine) products that the LDS likely sold out of.
It can get kind of like the fast food business. It only looks like they're in the business of selling hamburgers and fries. They're in the business of moving money for float, etc., owning real estate, etc., very much larger and very much longer term issues than getting paid Tuesday for hamburger today.