Having trouble with money at lvl 40 to buy your mount?
Here is what I have done with all of my toons in order to make sure that I will have enough cash at lvl 40 to buy my mount:
1. Pickup 2 gathering professions (mining/skinning/herbalism). I would suggest going with Mining and Herbalism; reason being, low level ore/bars sell better than low level leather/herbs and mid level herbs are very abundant and sell for good coin for mid-level toons.
2. Never pass up a node. I have found that a lot of players will pass up nodes or forget to turn on tracking. Get in the habit of switching the resourse you are tracking and never miss a node. Node = $$$
3. Make an alt to store excess materials. At lower levels, bag space can be horrendous as we all know. So make an alt to store all of those mats you'll be farming so you don't start passing up nodes because you don't have the space.
4. Know your economy. Every sever is going to have a different economy. Get in the habit of checking what each resource is selling for every time you are in a city with an AH. If you end up taking mining, don't forget to check how much ore is going to be selling for as opposed to smelted bars.
5. Once you hit level 40 and have followed the above steps, you will most likely have the money for your mount. At this point, you can continue with the same process (although the income tend to slow down from 40-60 with raw mats other than high end herbs) or you can drop one of the gathering profs and pickup a complimentary crafting profession (mining=eng/blacksmith, skinning=leatherworking, herb=alchemy)
6. Tailoring/Enchanting: The reason these two are complimentary are that levelling tailoring provides you with a lot of green quality items that can be disenchanted for raw materials to level enchanting. I have not had much luck with making a lot of money with these two professions at lower levels, so keep that in mind.
Other things to keep in mind:
1. World of Warcraft Tailoring Skill Up Guide
Above is a link to a site that has power leveling for crafting professions. I have found it extremely useful for catching up my crafting profession once I hit level 40.
2. Mats that sell well:
Mining: Copper / Iron / Mithril Bars. I have found these to be hot sellers no matter which server I am on.
Herbs: Swiftthistle, Fadeleaf, Khadgars Whiskers, Kingsblood. Although I'm sure there are many more, these are the ones that immediately come to mind.
Leather: This I find changes constantly on any server. In my experience, Thick and Heavy leather hev had the best luck for me.
3. AQ War Effort:
If this event is active on your server, find out which materials your faction needs to turn in and sell the hell out of them. People typically buy these materials in mass quantities and the AH runs out quickly causing the price to inflate rapidly.
Hope the above is useful in some way or another. I has surely worked for me as a tried-and-true method of avoiding the frustrations of the level 40 mount grind.