Meh tired being a lazy leecher, so here's what I have to add.
With 3.1 inc, it's time to be smart.
Saronite on many realms goes for only 15-20g/stack (even less if you find that lucky chinese farmer that wants to sell you a ****load of no money) - Prospect the shit, get huge loads of gems, save them for 3.1 - if you got rare recipes turn them into gems, save them, if not make some people create a lot of them for you. With all the uncommon gems you either sell them to ppl who pays 2g each to make them into enchant mats and resell them, but better if YOU can do this, since that will make it possible for you to save a load of enchant mats and gems for 3.1..
The thing is that in 3.1 endless amounts of epic items gets replaced and if you put these materials on AH around 22:00+ people will show up after raid and want to enchant/gem their new gear.
Even better would be to make enchants like resilience on chest, sheild, etc on scrolls and save them for 3.1 since 3.1 will introduce new pvp gear, and a new archavon boss. 3.1 will also introduce the dual spec feature, and that means a lot of people wants to gem and enchant their offspecs / other gear sets = AH _will_ get ripped for mats.
Another way to make money is to create/buy cheap a lot of glyphs that gets buffed soon.. for example:
* Glyph of Arcane Missiles -- Increases the critical strike damage bonus of Arcane Missiles by 25%. (Old - Increases the range of Arcane Missiles by 5 yards.)
* Glyph of Mana Gem -- Increases the mana recieved from using a mana gem by 40%. (Up from 10%)
* Glyph of Arcane Blast -- Increases the damage from your Arcane Blast buff by 3%. (Down from 5%)
Glyph of Seal of Righteousness -- Increases the damage done by Seal of Righteousness by 10%. (Old - Reduces the cost of your Judgement spells by 10% while Seal of Righteousness is active.)
etc etc - buy this cheap now and sell it high in 3.09 / 3.1
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Some of this might be common sense, and repost and whatever.. but just sharing.. I might add more later.