I should have mentioned one other thing. There are plans that use primarily thorium (the ones mentioned in Kheim's post). Stick with those. There was one item that I made a lot of that required 20 thorium bars, 4 green power crystals (found like herbs in Un'Goro Crater), and 8 rugged leather (bought all mine off AH). That was the cheapest item I could make for skill gain. I had to spend a little more to get from 295 to 300, but it is smooth sailing for a while after that.
Ever since TBC came out, enchanted thorium and arcanite is of little use (too hard to find enough arcane crystals) and the mats are too cost-prohibitive to use as a leveling skill. For example, one item that I can make requires 8 Azerothian diamonds. I have never found one of those and it would cost a mint to buy them on the AH (assuming to can find people who have some for sale).