Patch 4.3 will be here any week now, so if you want to make a bunch of gold you need to stockpile materials at the pre-patch prices. Once the patch hits, prices will increase across the board for all the necessary materials for crafting and enchanting. This patch will have several new dungeons and raids, plus the PVP recipes are getting buffed. Blizzard is also introducing a new looking for Raid feature. This means loads of new gear that needs gemmed and enchanted. So clear out the junk in your banks and start stocking up on martials now. Even if you don't have a crafter you will still be able to flip a lot of these items for nice profit.
PVP gear: With the PVP recipes getting an increased iLevel they will be a hot seller for the first couple of weeks. You want to make sure you have all the materials on hand to be able to make them right at the start. Even if you don't have a crafter you can still buy a bunch of the materials now for cheap and resell them after the patch hits. The materials needed to make the PVP gear would include Embersilk Cloth, Savage Leather, Elementium Ore/Bars and Volatiles.
Leg armor: All the leg armor and threads should see a big increase with the new raids.
Enchants: Everyone is going to have new gear that needs enchanted. This means that not only will enchants sell but also all the enchanting materials will rise in price also.
Ebonsteel Belt Buckles: New belts will need new buckles.
Gems: Even though Epic gems will be available it does not look like they will be abundant, at least not at the beginning of the patch. This means most players will still be buying rare gems for their new gear. Shadowspirit gems should also sell well since more people will be raiding with the new search tool.
Right now rare gems are at an all-time low price so you could grab a bunch now and resell them as soon as the prices go back up. I would stick to the prime cuts like strength, agility, and intelligence.
If you can stock up on these items now, you should make a bunch of gold the first two or three weeks of patch 4.3. Even if you don't want to stockpile a load of materials this is a good time to buy some extra gems and enchants for your own toons so you won't have to pay the inflated prices that are sure to come.