I've turned in all 9 every fair, in fact this fair, it cost me a total of about 2k, for ALL 9. with highest being treatise for 1k. (it's gone down a lot isnce they hotfixed the bug where it wasn't dropping hwere it should be). The raid and PVP ones are a joke to get yourself, that puts you at 4 at no cost (raid one drops in LFR now btw, although you can probably get one off AH for less then 1 gold now as a result of that change). the 5 dungeon ones have gone up a little. but if you were smart and stockpiled them the first month you're set for months/years to come. If not. then yuo can sitll get them fairly cheap, 100-500g in most cases. You also had an entire month to farm them, none of which are really that difficult to get anymore. treatise is only one that actually requires heroic, the rest just require mobs b green. i could get an egg for example just soloing a level 80-81 dungeon.

Should the bug be fixed? apslutely. Is it gamebreaking? Only if you're not willing to spend more then 5 min a month actually TRYING to complete the achievement instead of complaining blizz put as much effort into fixing it as you did in getting it.