You can do the tub in a weekend, it isnt that bad at all, and rolling it produces a texture that is indistingusible from spraying, so why spray(unless you have one already). You will be under 200$ to put down the Monstaliner, 134$ for the tintable kit with roller and scuff pads, 34$ for the tint, 12$ for 1/2 gallon of xylene and a 1$ for a 2gallon bucket. Far less than your 400$ estimate. The only thing is your time, which should be worth 300$