Many of the reagents can be found in the Bazaar, some through gardening, and some through transmuting one or more reagents to make another more rare one that you need.
Depending on what you need, you might also check the reagent vendors in the various worlds, as many times, some of the reagents you need can be purchased there cheaper than in the Bazaar.
and I want the spell so where could I find the regiments for the spell