It's hard to say with me because I've been pulling from the same pool of gold for so long. I have the 50 mount achievement on my DK and fully gemmed and enchanted gear on my DK and priest. I also leveled cooking to 400+ on my DK without actually gathering any mats or finding recipes.
It definitely helped that I really didn't pay out much gold for gear. I paid for a titansteel destroyer on my DK before the finder came out and made gearing up a joke, but aside from that, emblems were easy to get when I seriously started working on gearing myself up. Aside from buying gems (since I took up alchemy, it's more like "buying a blue gem, transmuting, and tipping a jewelcrafter," but I digress) and tipping for enchants, I basically got all of my gear for free. I never paid for BoEs or anything, I just geared up from ToTC25 (one of my trinkets), VoA, frost emblems, and ICC10/25. That alone saved me quite a bit of gold; I remember seeing how pricey the Dalaran rings are.
Oh, I also have the gigantique bag, so I don't have a problem with blowing lots of gold for achievements, apparently.
So I guess I did pretty well for myself, all in all. I think at my peak I had about 10k gold between my toons. Right now, on my main realm, I have about 7k total at the moment. I used some of it to found a bank guild ("CowMart Inc"), which has proven to be insanely useful when it comes to leveling my toons. Having a shared bank is niiiiiiiiice.