Blacksmithing and Enchanting are, by a significant margin, the most expensive. While Highlander correctly points out that most smiths and enchanters will procure the materials by their own means (mining or disenchanting) rather than buying them, those mats still have an inherent value (i.e. they could be sold at the AH), and therefore I think it's fair to say they are just as expensive as they look. Note that there is no number for the 300–375 part of jewelcrafting because Highlander says costs vary too much to give a solid estimate. For the raw numbers and more discussion, take a look at Highlander's post.