Generally, you have a mold that costs X, this is a metal mold with zero undercut, the default build area for the typical injection mold is roughly 6 inches square and costs, ballpark $3000 US. That gets you four poses.
After a hit is pulled from that mold, they get dropped into separate buckets. One for each part or figure.
If there is any assembly, then the figs go to a chemical or sonic welder. This costs money also.
Then you have paint.
Generally, in a chinese style factory, you have vacuum formed molds from which are cut out the areas that require a particular color. Each color requires a bay, airbrush, worker. The figures go from bay to bay, each bay providing one more color or shade. Each vacuum pulled template can only cover about 180 degrees of the figure (but you can't use all 180 degrees). Generally it takes 3 templates, per color, to fully paint one figure.
Inking and drybrushing counts as a shade.
Then you have any fine detail work that may require a hand application of paint. This is especially true if the detail is such that it was not possible to do a template paint job.
Then you have pad printing (insignia), one color per bay.
Then you have packaging, inspections, and shipping to deal with. Which, hopefully stays more or less similar per item to make packing the shipping container easy.
Every penny of additional cost translates to 5 (minimum) or more cents of final retail cost. Then, the cost of the original mold that started all of this gets divided into the cost of the entire production run. So, the fewer molds needed, the cheaper the figures can be. If the initial run sells out.. then WOOHOOO... the reprints make more money since the molds are paid for. (Congrats to Mongoose if this run sells out!) This translates to more product for us, the fans.
...this assumes the molds didn't come off the Open Market (which it doesn't sound like that's the case here).
BY NO MEANS does it cost the same per figure - even if they are generally human sized.
I have absolute confidence that Mongoose is charging a fair price per box, and that the boxes are grouped/ganged in such a way as to be as easy for them to ship and sell to distribution as they are for us to buy. Same pricing/similar pricing is just bloody smart business - and packaging the figures to GET this kind of similar pricing is logical.
/sigh
I miss Hong Kong and the Canton Toy Fair... many happy memories there.