Eh. The tanks are very nice. But IME they do not fill up the tire faster than my OBA. At least on a 35" tire. (5-35psi ~ a minute for either) My OBA is the stock toy AC pump.
Putting it together is the cheapest, but you need to know someone in the biz to find used items for cheap. If you find a used tank/regulator for cheap, that's the bulk of the cost. If you can't find them cheap, you spend up to ~ 200 on those two pieces alone.