Lol okay I will go with that one then....I just wont shower for a couple of days since I don't take baths lolI think the one you've chose is good. Its what most would recommend if you aren't doing a more expensive one from BRS. I just remember finding a chart out somewhere that had the prices and there's were more expensive. But its all less than going and buying water.
And all of them are going to have serious waste. Like a 1/4 ratio some less but you're gonna get like 1 gallon for every 4 or something. Take one or two less baths and take a shower and they even out really. Filling up your bath tub is a lot of wasted water.