There used to be a page here on this site about them, but I can't find it anymore. Might still be here but buried.
They were only made 1 year (though 2 different models were released in 2 consecutive years) and made by 2 small american luthiers (a different one for MA1s vs. MA 2s and MA3s) to Ibanez specs. Apparently 1) it wasn't cost effective for Ibanez, 2) the small luthiers couldnt keep up with demand, in any case, they were discontinued after one year each. I've heard various claims about the names of the luthiers that actually made them. Googling those names yields squat except the references to those names here. I doubt Ibanez farmed these out to someone no one has heard of before or since. Probably only Ibanez knows for sure, and they arent telling.
There were very few made. I've heard various estimates, but never heard anyone claim that more than 100 of each model were produced.
What sets them apart is they are handmade USA instruments and it shows in the quality. They also used very good wood. For example, the highly figured birdseye neck on my MA3 is very stable, and that guitar is strung 12-56 at standard pitch, almost never needing a truss rod adjustment for seasonal changes like nearly every other guitar. From what I understand, they also used Honduras Mahogany (i.e. real mahogany) not the bull**** fake mahogany (khaya, agathis, etc) that most guitar companies call 'mahogany' nowadays. I could go off on a rant about that practice alone..
In any case, having owned RGs, JEMS, RGTs, etc, I can tell you flat out, none of those has the playability or quality of the American Masters. Its something you can feel and hear. There is no 'super strat' style guitar ever made, by any company, that I'd take 2 of in trade for my MA1.