Tinner said:Tiny creature is something the size of a cat.
Average weight for a cat is 7-12 pounds.
According to the PHB page 112 there are 50 coins in a pound.
So the proper amount should be 350 - 600 gp per tiny fey.
Of course, being innately magical, a fey may very produce more gold than "science" would expect.![]()
If fey are the same density as humans, their density would be a little less than water. If they were turned into pure gold while retaining their volume, their weight would increase by at least a factor of 19.3 (the specific gravity of gold). So Tinner's numbers would have to be multiplied by a factor of about 20. A creature can be tiny and weigh a lot less than a cat, though; many fey are very slender indeed. 1000 gp is a very conservative lower limit. Of course, the fey might be hollow after being transformed.
As a guide to how much money a spellcaster can make casting spells, the fee for NPC spellcasting is around caster level x spell level x 10 gp. You actually need to have someone want you to cast the spell, though; you can't just cast spells all day. This spell requires a hard to get spell component, though; the
The other way to make money through magic is through the construction of magic items. Each 25 gp of market price costs 12.5 gp in materials and 1 xp of personal energy. You are more or less turning xp into gold at the rate of 1 xp = 12.5 gp profit.
If you combine these two calculations, I would say that an xp expenditure should be no more than about 50 xp per casting. Assuming 1000 gp fey, that is. 6000 gp fey would be a different story.