I used to use the AddOn OreCrusher a lot back in 4.0, however it seems that it is out of date for MoP. Is there any alternative available for MoP?
If you're not sure what OreCrusher is, it was an AddOn that would pull information from Auctionator etc. and showed you the best way to make money with your ore, whether it was selling raw ore or prospecting the ore and cutting gems. It even went as far as telling you if making them into enchanting mats was the best thing to do.
Link to OreCrusher.