You can make one from an old water heater for about $250 (minus the heater, but you can get it for free). Look up "appleseed processor" on the web. The most expensive part is the black iron pipe and fittings. You can't use galvanized pipe because the caustic chemicals can react with it.
Get a couple of barrels for storage tanks and a washing/drying tank.
A lot of people replace their water heater for a lot of reasons, and 99% of the time, the tank is not leaking. The only reason you want the heater in a biodiesel plant is for the insulated tank, so pull one out of the trash if you can.