I was at 14,000 gold until I spent a bunch on some items for my shaman and am at... about 11,000 combined now (two 70s). I don't farm gold very hard, I will do between 3 and 7 dailies in any given day, or as many as 15-16 on rare occasions. Even so, if it gets to be a chore I just stop for a few days. I also made around 2,000 gold selling the enchanting mats from the items I was DE'ing while boosting the alts. Heck I may have made 2,500 by now, dunno.

The only real expenses I have coming up are the level 60 mounts for my four alts (~2500?) and the level 70 mounts (~3500?). And I plan to leave most of the quests available for the alts to do at 70, and those will bring in enough gold to cover the mount expenses and then some. Blizzard has given players pretty much every option available to gear up and get the things they need while spending very little gold, and at the same time they have made so many ways to make gold by the bucketful. I am planning to have at least 10,000 gold on hand when the expansion goes live, and may have as much as 20,000 or more. And I plan to be very very cautious about spending it, unlike the past.