Most of TBC trade goods are more valuable than their Wotlk and Cata equivalents. If you want to make some additional gold, it's wise to check TBC items' availability and price out from time to time.Do you want more gold tips? Don't forget to share!
Prospecting Adamantite Ore
To create Mercurial Adamantite, you need the following items and skill.
Adamantite Powder, on the other hand can be a bit trickier. Sometimes they are so valuable it's not profitable to turn them into Mercurial Adamantite. Sometimes they are dirt cheap. This depends a lot on how much Adamantite Ore there is available, because Adamantite Powder comes from prospected Adamantite Ore.
Nothing to prospect!
If there are no Adamantite Ore available in the auction house, it's wise to prioritize mining it instead. A stack can very well sell for even 400g if there is no one undercutting you. But don't forget to put it into other uses aswell. Smelt some of them, create and sell a few Mercurial Adamantites, Adamantite Powders and any other valuable Adamantite items that comes to your mind.
And if you are not sure how much you should sell some for, start from bigger numbers, and reduce them if it won't sell. I've sold Mercs for even 600g each and Adamantite Powders 150g each. There's little competition and the prices like to stay high.