Get and/or raise your negotiation skill. The price of identification will drop dramatically. At the beginning, only identify items you're thinking of equipping. Take the price hit until you've got the negotiation skill.
Take easy fetch quests or delivery quests. Keep an eye out for delivery quests that go to the same town, but remember to check how many days you have to complete it.
There is no way to buy platinum with gold. They're rare for a reason.
There are two types of mutations:
The regular mutations are affect your attributes, a few potions, fountains, dreams, and monster attacks can cause mutations. These can be positive or negative. They can be cured by drinking potions of cure mutation.
The other type of mutation is the Mutant feat, which lets you randomly grow a body part. Mutants start out with this feat (But only start with four equipment slots). All other races can get it by using a "Secret Treasure". There is no way to remove it though. Keep in mind thatthe slots you get are random. You might end up with even slots, but there's always the chance of growing 12 heads if you're really unlucky.
There are no official custom races yet, I made those myself with a hex editor. There ARE debug races though.