There is a very easy way to make decent platinum at relatively low levels,
like 10 and above, perhaps even a bit lower.

There are two aqua goblin camps just south of the Butcherblock docks, along
the shore. The goblins there are about level 8-10 and drop 4 items that are
worth 4-5 plat each, depending on the merchant, and your charisma. The
goblins are aggressive to everyone, it seems, and will gang aggro.

Backbones, Dirjadak's chipped stein, aqua goblin heads, and goblin blood are
the good drops. The backbones and blood stack, the heads and steins do not.
so take lots of backpacks along. I made over 300pp there in about an hour
with a level 14 magician. The biggest problem there is finding a time when
these gobbies are not camped. Don't sell to the high elf merchant in the
ruins nearby, he is a cheapskate. Wait till you have tons of loot and then
trek over to Kaladim, if your faction allows. I have gotten decent prices
from Vacto Molunel, at the entrance to the warrior's guild.

A few trips there, and then to the Bazaar, and you can be decently equipped
without twinking.

Froondor, 46 druid
Squiddles, 16 magician

and a host of others, on Tarew Marr and Zeboxuruk