Just got the trophy for having all magic spells, figure I'd make a post with a complete checklist. Doesn't have all the locations yet but the majority are bought, I'm sure the thread will expand as people ask questions / comment. They are listed in the order they appear in your inventory.
A slight bump, where do you find 'Hush'? It seems to be the only one I am missing. I bought all sorceries from the apprentice, logan in Duke's Archive, and the lady by the Hydra. I'm going to assume this is found as a treasure in some world, but where would it happen to be? About to hit NG+ so every area is available to me.
Demon's Souls/Dark Souls Stat and Weapon Calcs http://sites.google.com/site/darksoulstats/