I bought them at the bazaar. The only annoying thing was I already have plenty of each of the snacks but it wouldn't count them until I bought more AFTER getting the quest. I think they should fix that.
Yup, buying at the Bazaar is the way to go. Saves you allot of time and bother in searching. Not too too expensive either so if you only have a bit of gold you should still be okay. Plus the training point can be helpful for sure!