Every player values gold in TBC Classic WoW and the following are some spots where you can farm TBC classic gold in a relatively quick way.
The first spot is Felwood. Here is a mob called Toxic Horor who has 7% drop chance of Essence of Water, which sells 10g-14g each. There are a bunch of herbs around too such as Plaguebloom and Dreamfoil to get some extra TBC gold.
The second spot is Winterspring. After completing a quest from Witch Doctor Mau’ari, you can get E’ko drops from the mobs around. E’ko sells 20 silver to 3 gold each depending on what kind of E’ko it is. What’s more, there are Black Lotus nearby which sells up to 50g each.
The third spot is where Bog Beast is. Although the location of this NPC is unknown, I have found one around the Essence of E’ko farm. It has 2% drop chance of Living Essence selling about 6g each.
Another spot is Un’Goro Crater. By killing Living Blaze there, there is 6% drop chance of Elemental Fire which usually sells about 1-3 gold each, and Heart of Fire selling 20-40 silver each, and a 4% drop chance of Essence of Fire which sells 3-6 gold each.
There is another spot in Felwood again for a jadefire run to farm Dark Rune selling 2-5g and Felcloth (5% drop chance) selling about 3g.
All in all, if you’d like to spend time on these spots, you surely will get a decent amount of wow classic burning crusade gold. However, if there’s not enough time for you to play, you can choose a gold-selling site and just buy a bunch there any time you want. There are a lot of such sites such as SSEGold.com which provide cheap and fast services. You could have a try.