I've got 6 vacuum trailers. They range frame $7,000-$14,000.  There are several makes and sizes. Dragon, VE, Troxel. I've got from 120 barrel to 160 barrel. All hold water without leaks and all valves are in working order. No aluminum tanks. All have 4 inch valves on the back of the trailer and some have belly lines. Everything is 4 inch but can be reduced to a smaller size. Would be a good oilfield trailer, water trailer to have on the farm or ranch, or if you fight fire and need a lot of water to fill the trucks this is your trailer! Call or text Jon @ 620-546-6340