I'm just wondering if there is anyone out there clearer than me at this point...

When it comes to the loot needed for bazaar items, is there a chance that you'll have completly missed out on being able to get some bazaar items, if you for instance kill a boss, and that very boss was the only source of -insert random loot name here-. Is there that possibility, or can you always find some other respawning enemy somewhere who also drops that loot?

God I'm not sure I'm making sense, no matter how I try to put this question down, it still sounds confusing. I hope I got my point across. It's just that I've heard somewhere that if you don't manage to steal this or that from this or that boss, well good for you, now you won't be able to get this sword/armour/bow/whatever from the bazaar. Then I hear others saying the opposite and I'm just not sure at all of anything.