I suspect most of us don't reply because your offices should have a fee schedule policy that outlines how to set new fees (i.e. what it's based off of, what multiplier to use, etc.). This answer is very specific to the practice and there is no one set answer. New fees have always been set by the Revenue Cycle Manager at all of my previous employers; coding was not involved beyond providing the new codes and their effective dates.
Having said that, I agree with VALJONES5959 - I think it's fairly common to use 300% of Medicare's fee schedule as a standard when setting new fees.