mining is great for making money, ZF groups will love to have you along so i would go there and make a ton of xp while saving up the greens you roll on... sell everything in the AH and ur good to go pretty soon
i know this is pretty ghey but sometimes when something comes along that i really need i get 100 gold off a trusted ebay store for $7.50 so i can use it right away and then save up my gold and every time i get over 100g, i put it back up for auction on ebay later

dont have to wait for your greens and minerals to sell that way...
or if ur like me and dont mind spending money on a game anyway and are just planning on grinding for gold till you get the amount you need... then consider how much gold you will be making per hour of actually playing wow. Then calculate other ways of making money in real life, like if ur a kid, how much would ur parents pay you to mow the lawn that week? or in my case, how much would i make for staying overtime for an hour today?
the way i see it, if i need something like a mount, ill stay an hour after work, make an extra 12 bucks for my time, then spend 15$ on 200gold... the time it takes me to grind 200gold easily would take way longer than an hour at the office and just sitting here getting some work done, or maybe goin oustide for a change in your case... of course spending money online or trusting some of the ebay sellers is up to you, and some might think its just wrong to spend real money on a video game, but when u have a choice to go home and waste time in front of your comp screen or make 12 bux overtime at the office and get 200g for it... it just doesnt seem like a bad deal lol...
tell me im wrong heh