Epsom salt is dirt cheap at any drugstore, like CVS. Baking soda and table salt can, of course, be purchased from any grocery store.
I have been purchasing gypsum, calcium carbonate and calcium chloride from homebrew suppliers, but I am sure there are alternatives to those ingredients as well.
The Fiesty(sic) Goat Brewery est. 2007 & Clusterfuggle Experimental Ales est. 2009
Planned: Fat Man Porter, sLambic II, Brettennial Falcon IPA, Flanders Red, Orange Blossom Mead
Primary: Winexpert Riesling Ice Wine, sLambic I
Secondary: Flanders Red
Kegged:Black or Blue EyePA, Cherrywood-aged Crystal Stout,
2013 dump volume: ~2 gallons