Profession costs
Over on the WoW-Europe forums, Highlander (of Terenas-H) has done an interesting analysis of the relative costs of leveling the crafting professions, assuming you buy all the required materials from the auction house. His pricing data is from WoWEcon, so it should be a reasonable average of costs on the various realms. Above you can see a chart I made from his numbers, showing the cost to get each profession to 300 as well as the cost to take it to 375.
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.
