Hello,
The master is really good. You are right that the most expensive part is the resin, which can cost even more than 500 USD per liter, this depends on the type of light which you use to harden the resin (other printers working with types of plaster are really expensive and the material is expensive, too). I am planning to build a printer at home together with a friend. This will use a liquid resin which is hardened by visible light. We hope to decrease the price for the resin to less than 100 USD per liter. And you have to bear in mind that the amount of resin per figure in 1/72 scale is less than 1 ccm (1/1000 of a liter)!
By the way, did you use a free sculpting program like Blender or Sculptris to create your master?
Best regards
Erhard