Heavy Leather can generally be skinned from Beasts around level 35-40. It is also obtainable from lower levels, but the chances are worse. If you are farming Heavy Leather for gold, I advise looking for buy wow classic gold cheap mobs at level 35+.
Gold per Hour: ~6-10 gold
Requirements: level 35+
Swamp of Sorrows
The Wildlife in this zone is right in our level bracket. While there is no trader close-by for Alliance players, it can still be quite a lucrative location. Just make sure to have enough bag space
There are several types of skinnable monsters here: Sawtooth Crocolisks, Swamp Jaguars and Shadow Panthers. All of these drop stackable grey items, in addition to the Heavy Leather. There are also Spiders here, and they might be worth killing as well. This is because they share spawn locations with some of the other wildlife. So the next time you come by the spot, there might be a Jaguar there. In addition to that, the spiders drop Silk with can also be sold for some extra gold.
And if you ever get bored of farming Heavy Leather here, you can switch over to farming Silk Cloth at a spot very near!
Badlands Heavy Leather farming
While the Badlands are similar in terms of location for the alliance, the mobs here a a little bit higher level, so they have a higher chance for Heavy Leather. Both of these spots have one great thing in common though: They have very low competition. The Cats that are all around the open areas of the zone drop stackable grey items, which can add up to some nice extra gold.
Stranglethorn Vale – a Blessing and a Curse
Most of the monsters in STV are skinnable, and you are more likely to find Beasts of the level we are looking for in the south of the zone. There is an abundant amount of mobs and traders here, everything you need! There is one big downside to the whole thing though: Stranglethorn Vale can be a very rough place to be for new players. It is one of the first zones in which world PvP is a big thing. Some people love this, some people hate it.
There even is a great spot for farming Thick Leather here, on an Island in there south.My conclusion: If you want some action while farming gold for your mount, this zone is right for you! But if you want to be left alone and farm by yourself, you should consider one of the other zones.