A machine shop has three options for a new milling machine. Machine Orpheus has a fixed cost of $$5,000,$ Machine Rex has a fixed cost of $$15,000,$ and the Zulu Machine has a fixed cost of $$25,000.$ The per$-$unit cost to operate the equipment is $$12$ for Orpheus, $$8$ for Rex, and $$6$ for Zulu. For what range is the total cost of a Zulu machine lowest?