Oh a subject near and dear to my heart...
Instead of buying expensive water why not try to work around the water you have? Unless it is totally useless like overloaded with iron or the like.
Palmer's nomograph and spreadsheet really helps in this once you begin to understand what the hell he is talking about. And there is a great series on the BNN's Brew strong (http://thebrewingnetwork.com/shows/Brew-Strong/Page-2
) all about water. It is a must IMO.
Just a few simple adjustments to my grain in the recipe
to account for my water profile dramatically improved the results without adding anything other than darker grains. Though, I evidently need to add some chloride according to Palmer's spreadsheet to make it "balanced".
Hope this helps.