Oh I see. Well we haven’t had such a request yet, but it would really depend on the idea and CG cost mostly.
If it requires CGs, for example for scenes or portraits or enemies, etc, it might go anywhere from 25$ to 70$, depending on the variations, complexity, etc. This is purely the cost of the CGs. Other than this we mostly do suggestions for free as long as they are simple enough or fit really well with the game.
If you want a very specific and complex thing I guess we’d have to discuss it, since it would really depend on effort and amount of time required :).