I just looked at how much we spent on our melamine rack that we made for our three boys. We spent about $245 (including any shipping) on the melamine (more than enough for a rack that holds 3 32 qt bins), thermostat (Herpstat 1), heat tape, and three 15 qt bins. We used plastic bowls as hides, ceramic ramekins for water bowls, and newspaper as substrate. You'll also need a decent digital thermometer/hygrometer ($12 at Walmart for an Acu-rite brand one), and feeding tongs/hemostats if you're feeding frozen/thawed (around $10 on Amazon). So you should definitely be able to get the tub set up for way less than $420, and still have money leftover to spend on the snake, rats, etc.