$3 a month to MAKE (manufacture) one persons monthly dosage, but common sense has to factor in profit/shareholders stakes, not to mention packaging, shipping, and all the other real costs associated with the actual mfg/distribution etc. That "cost" reference point means nothing with regard to actual selling price point. I'm going to go out on a limb and suggest it's already well below that cost per "monthly dose" and has been for quite some time, after amortization of production facilities/equipment, etc.
If we're getting X MG for Y $$ you rest assured the cost isn't -2x to -3x what we're outlaying, more like -10x to -30x, so more accurately I'd think even now they are at "pennies per dose" versus the cited "could be as low as $3 per".