That's a good question.....which took me to the Kalmbach online store to investigate. It appears to be one of those graduated shipping charge schedules that becomes more cost-effective for the purchaser the larger the order. A lot of companies do that. For one magazine, you're right, it's not very cost effective, but for three magazines, you'd still be paying the same shipping charge. For six magazines, shipping's a better deal, and so on. Maybe there's a couple-five-dozen or so other back FSMs you'd like?
When I order from places that do ship charges this way, I work really, really hard to make sure my order total comes in very near the top of a shipping charge range. I've been known to hold off on buying an item just because it would put me just into the next range.
But then, as my fellow FSM staffers remind me, I'm cheap. Really cheap.