Mega Snacks (rank 8 and 9) have been no auction for quite some time. Sorry, I don't know how long ago it has been but i am sure it has been over 6 months.
Any item, including Mega snacks that say "No Auction" can't be sold at the Bazaar. These items have to be sold at a shop vendor in other parts of the game; like in the shopping district or to Zeke.
I myself have never seen Mega snacks for sale at the bazaar though I have seen level 6 snacks, crafted and such. Honestly I can not really understand why anyone would want to sell Mega Snacks anyway.
Mega Snacks used to be available at the Bazaar, however, when gardening came out, KI made some plants give mega snacks... Now, this is a good thing, however, there was, at the time, a way to exploit this and keep harvesting elder plants, by stacking them...
Now, some people that exploited this, kept selling the mega snacks at the Bazaar...
Wizards101 went down to fix this and punish the guilty culprits by means of Ban... However, the rest of us, also had to pay for their exploit...
Since so many mega snacks were for sale and because we were given a way to get a few mega snacks by gardening, KI deemed it necessary to make them a no auction item to make up for loss in crown sales...
Although, back then, people would buy tons of Mega Snack Packs and sell them for gold...
I do not agree with KI's decision, but there is nothing I can do about it...