Professions cost a lot wow gold

2 gathering professions, herbing and mining are the main ones to make wow gold with, also skinning as well
skinning is more predictable, and you control how much you gather through killing things vs randomly finding nodes other players, botters and hackers havent hit.
Also, I would KEEP everything you get while wow powerleveling your gathering wow professions. These things are extremly useful when leveling up another profession on another toon( mining for JC/BS, herbing for inscription/alchemy) and wouldnt you know it, the minute YOU decide to power lvl one of those professions, all the lvling mats are 300% over average market
wow gold price. but hey you have some saved up, so you just saved yourself some wow gold.
Keep an eye on everything that you gather, and their
wow gold prices in the AH(Auctioneer is an awesome tool for storing prices, and means and averages of wow items)
ALso keep in mind that certain professions feed off each other, if you have multiple toons. Good example is:
Mining feeds JC (prospect and sell uncut and cut wow gems)
JC feeds enchanting(disenchanting low cost(you farmed
wow mats etc) wow items made by JC) to sell enchanting wow mats/actual enchants on scrolls
Doing something like stated above will enable you to undercut to almost any wow gold price(above vendor
wow gold price) and still make a profit because HEY you didn’t BUY them with wow gold off the AH, you farmed them without using wow gold.