Enchanting: Buy now, sell later

Just a random selection of enchants with threshold set to current market values

Many Enchants are currently priced way under market value, from the small example above let's highlight Enchant Shield - Blocking. This is an Enchants requiring 12 Hypnotic Dust, which on my server are 15g each on average. The Enchant should be worth about 200g yet due to increased supply from people leveling Enchanting it's currently available for a bit short of 12g.
I've bought about 50 scrolls of this particular Enchant so far, every single one below 15g. My reasoning for this is since there is only one alternative (Enchant Shield - Protection) which in my opinion is inferior to this one. Demand for this Enchant is going to increase while supply is going to decrease. However, don't forget prices for Enchanting mats are going decrease as well as lesser mats are needed to level professions. For this Enchant I'm buying risk free, Hypnotic Dust will never go as low as Infinite Dust did halfway through WotLK due to inflation. Infinite Dust bottomed out at 1g 50s on my server which calculated back to 18g for the Blocking Enchant.

The risk for every single Enchant can be calculated like this. When calculating also keep in mind there will always be people leveling Enchanting and they will dump their scrolls on the Auction House. If that supply beats the demand for a scroll it might never recover from the price deflation we're currently experiencing.

Note: It's probably going to take many months before reaching your ROI for these scrolls. Do not invest if you want some quick easy gold!

Levelling enchants

Since most 'end-game' enchants aren't selling this close to Cataclysm I decided to list all levelling or twink enchants. I've noticed an increase in sales for enchants like Crusader and Mighty Intellect in the past few weeks so I figured there was more gold to be gained from these enchants.

I've created the following list based on two criteria:
1. The enchants can't have an item level requirement
2. The enchants have to give a significant bonus

Based on these two criteria I've selected the following list of enchants. Some of these are quite hard to get if you don't have them already, be prepared for some reputation and AQ20/40 grinding if you want to collect all of them.

Cloak
Enchant Cloak - Stealth (melee & hunters)

Chest
Enchant Chest - Greater Stats (all)

Boots
Enchant Boots - Greater Agility (melee & hunters)
Enchant Boots - Minor Speed (all)

Gloves
Enchant Gloves - Greater Strength (melee)
Enchant Gloves - Healing Power (casters)
Enchant Gloves - Superior Agility (melee & hunters)
Enchant Gloves - Riding Skill (all)

Weapon
Enchant Weapon - Agility (rogues and dualwield hunters *)
Enchant 2H-Weapon - Agility (hunters *)
Enchant Weapon - Crusader (melee)
Enchant Weapon - Healing Power (casters **)
Enchant Weapon - Mighty Intellect (casters)
Enchant Weapon - Spellpower (casters **)
Enchant Weapon - Fiery Weapon (melee)
* Will become very expensive to craft with the changed droprate for Essence of Air
**Not everybody is aware of Mighty Intellect being the best enchant for casters since 4.0.3, don't underestimatie the selling potential of well known enchants.

Shield
Enchant Shield - Greater Stamina (all)
Enchant Shield - Vitality (all)

I don't have all of the enchants yet but I'll update this post after some time when I have a bit more information about which enchants actually sell. Unfortunately the amount of expected sales can't be directly linked to the quality of an enchant, otherwise I'd see much more Mighty Intellect sales instead of Spellpower or Healing Power.