Another player commented to me the following.
"On a side note, Soft, there's no benefit, RAW, to taking Magical Artisan with either Extraordinary Artisan or Exceptional Artisan: the latter two feats refer to the base price/time to create the item, the former refers to the normal cost to create the item, and despite being worded differently in the feats they are technically the same thing. They don't stack because the both reduce the same number by the same percent; reducing a 1000 GP base price by 25% and then only having to pay 75% of the normal 1000 GP cost doesn't drop the cost down to 500 GP, or even 562.5 GP. Every discussion I've seen on the topic has either ignored the wording completely, or pretended that base price and normal cost are somehow not the same thing (at least when Magical Artisan affects the Exceptional/Extraordinary Artisan feat directly; see my edit below).
For the record, I honestly wish they did stack RAW, if only because creating magic items is a huge pain the ass and takes forever once you hit more than a few thousand GP base price, and squeezing as much reduction in time (if nothing else) out of feats makes it at the very least tolerable for both the crafter and their companions, but short of Joey word-of-godding that they do, RAW, they just don't stack with each other.
ETA: Just to be clear about the above, I'm referring specifically to using the Magical Artisan feat and selecting Extraordinary or Exceptional Artisan as the Item Creation Feat it modifies; the problem goes away if applied to a feat used to craft a specific kind of item (like Craft Wonderous), so long as you apply the MA adjustment first and then the EA adjustment. (This technically isn't possible with MA being applied to EA, because in order for MA to apply at all, you first have to make use of EA, and in that particular case the base price and normal cost are the same; in the case of MA being used separately, the normal cost is reduced, and everything is then calculated from this new base price, which is NOT the case in the former.)"
This looks to be correct to me at least. I was looking for some feedback stating why they would work together.