& btsetpartcost()
 
  Syntax: btsetpartcost(<partname>,<cost>)
 
  This function sets the cost of the specified part.
 
  The function returns the value that the cost was set to.
	
	Note: <cost> must be numeric. If a non-numeric argument is used the 
  cost is set to 0.
	
	Note: The information manipulated by this function requires the bt-
	advanced-econ compile-time directive.
 
  Error Messages:
 
  * If <partname> is not valid the function returns #-1 INVALID PART 
     NAME
  * If the mux was compiled without the bt-advanced-econ directive 
    the function returns #-1 NO ECONDB SUPPORT 
 
  Example:
  Given that VTOL_FUEL is a valid part
 
  > think btsetpartcost(vtol_fuel,500)
  500