Figured I'd post this since the game isnt really going anywhere anyway
The commodity item 'Tome of Blacksmithing' is currently 'bugged' where if you buy 4000 or more of this commodity at once it will give the you the input limit reached error and then not only return all the gold spent, but gives you all the tomes you just bought, essentially duping your gold.
Seen it pop up on bug reports on d3 forums so it will probably be fixed soon, have fun with it while you can.