In Path of Exile, there's no gold (piece) economy. It is based on currency items which each have their own use and their prices are relative to themselves, and to the leagues in which they appear. What is the use of these currency items? Crafting.
However, it's not hard to tell that burning high value currency on low-level gear is a...wasteful endeavour. It's nice to have good mods on low-level gear, but these items are not like the more eternally-valued end-game gear. People may suggest trading for the sort of gear that one desires instead of trying to craft it oneself. A good way to put it is that, largely, crafting is gambling.
I could go on, but I want to leave the rest to the answerer.
When should I wait and when should I create?
When should I pump it and when should I lump it?
When should I leave it and when should I conceive it?
When should I buy it and when should I apply it?
When should I ditch it and when should I hitch it?
When should I damn it and when should I spam it?
When should I whet it and when should I forget it?
When should I hone it and when should I disown it?
OK, I'm having too much fun.