you could make the Cost To Run parameter a Description Text (eg “The Cost To Run is $3.25”). which would be visible upon entry but not particularly useful afterwards (eg cannot be Summed or Averaged, etc), or
a Calculated Currency (e.g “=3.25”) which is more useful but would not be visible until after entry
a Dropdown (eg 3.25, set as the default), which would be visible upon entry, useful afterwards, and if it ever changes, could preserve the historic data by adding the new cost (e.g 3.75 as the go-forward default) and hiding the 3.25 option