Other sites (including wow.joystiq.com) will contain a breakdown of this event (this link is last years faq), but I have a few things to add. Many alts are currently being levelled, many of which don't have cooking. (even some of mine). For those toons that get the festiva'ls shortcut to 300, many will push on to 450.
- Tracker snacks allow you to track turkies for the turkinator. People wont buy them unless you advertise it in trade/outside the relevant areas. Once you advertise, others will enter the market. So make a stack or two, post them (individually) then advertise them.
- Recipees to fill the gaps - essentially 300+ will be popular
- Raw mats to for the 300+ recipees will sell out -extra points for posting mats for the easily obtained recipees. If you are planning on levelling skinning or fishing soon (or now), keep this in mind.
- Northern spices - obtained via the Dalaran cooking dailies will be in short supply. If you do dailies and have cooking, add this daily to your list.
- For those that do get near 450, noting that many (most?) festival participants won't, mats for Small Feast and Gigantic Feast will be in short supply.
- Mage portals will be very popular
- Enterprising warlocks who can co-ordinate a small raid might be able to hustle in on the portal business - with the added bonus of directly porting toons to the festival grounds.