Bags are a constant item in WoW. Every person needs them at some point while leveling their character. There are bags for nearly every single profession and also generic bags too. Lets look at each of these bags and where they come from.
The generic bags are the bags that are made through tailoring. Several of these bags sell rather well also. The ones that sell well include the glacial bag, abyssal bag, frostweave bag, embersilk bag, illusionary bag , and of course the netherweave bag. The mats of most of these bags can be gotten cheap enough to allow you to turn a large profit on them. I would recommend saving your dreamcloth instead of making any more illusionary bags right now mainly because of 4.2 and the new recipes coming out. Netherweave bags tend to sell in groups of 4 so I would recommend posting at least 4 of them at a time. The mats for the frostweave,abyssal and glacial bags can be bought pretty cheap usually and they usually sell for the same price as an embersilk bag.
There are actually two herb bags that sell quite well. The wrath version of it is the emerald bag and the cataclysm bag which is the Hyjal Expedition Bag. You can usually sell at least two or three bags a week.
Again lets look at two enchanting bags in case the market for one could be bad. The Mysterious Bag is the wrath version and the mats price for it can be cheap sometimes. The Otherworldly Bag is the cataclysm enchanting bag but it is kinda unique in that it uses wrath enchanting mats to make it. This tends to make it one of the cheapest specialty bags to make.
There's only one jewelcrafting bag and it is rather small compared to the other specific profession bags. It's called the Bag of Jewels and it only has 24 slots. People tend to buy it though because profession specific bags will automatically sort your inventory for you so it makes it easier to manage your auctions. The mats are easy enough to get and it will sell for triple the price of mats easily. There usually isn't a lot of competition on these bags since its a rather niche market.
All of the previous bags could be made through tailoring. These next bags including this one are all made through leatheworking. The only mining bag of note to sell is the Mammoth Mining Bag. Mats are very cheap and can also be easily farmed.
The one inscription bag of note is the Pack of Endless Pockets. It is a very useful bag for glyph sellers and in very high demand. The mats are exactly the same as the mining bag so you can expect to get them quick and cheap.
The one leatherworking bag to take notice of is the Trapper's Traveling Pack . It is the largest bag for leatherworking and also skinning so it is a decent seller too. The mats are the exact same as the previous two bags made from leatherworking.
These next two bags are both made through engineering. There's only one engineering bag that seems that sells decently. It is of course the Elementium Toolbox. The mats should be rather cheap on most servers because of the price of elementium ore.
There's a fishing bag it seems. I've never actually attempted to sell one but I could see it being useful to some people. It is called the Lure Master Tackle Box. Its mats make it fairly cheap to craft. If it sells tho, I've honestly no idea on that one.
There were quivers, bag to hold ammo, for hunters and soul shard bags,bag that hold soul shard for warlocks, but both ammo and the amount of soul shards got destroyed in cataclysm.
Well that wraps this post for today. Hope you enjoyed it.