So I decided to change Mining for Blacksmithing. I have mining on two other toons so i thought i'd better give my main a profession boost. "OMG" upto TBC BS has become quite cheap to level. As soon as Fel Iron and then Cobalt bars were needed the price skyrocketted. A stack of Fel Iron bars cost 100g and Cobalt bars are currently going for 60g per stack.
I could see my gold dropping and THEN it came to Cataclysm mats. I dropped roughly 20k into levelling Blacksmithing to (currently) 520. With this I purchased nearly all patterns from the Twilight Highlands vendor and levelled to nearly max level in around 3-4 hours.
I used one of my other miners to smelt ores if it was cheaper than buying bars. Obsidium ore was alot cheaper than bars and elementium ore also. I have currently 800 elementium bars left which should help me get some epics crafted should I get lucky on the chaos orb rolls. I bought all PvP plans so I will most likely get some of those crafted and sold on the AH for all those new level 85 PeeVeePee'ers.
I think that I will maybe make back half of the 20k from sales/crafting but in my mind a 10k loss to powerlevel a profession such as Blacksmithing at this time after the new xpac aint half bad.