might want to check out dry ferts.
http://www.bestaquariumregulator.com/ferts.html
http://www.rexgrigg.com/ferts.htm
while when you buy in bulk it would be less but you get the idea.
that was the most confusing site ever. yeah I got tons of ferts, but still do not know squat on what to give my 20 gallon tank, my 10 gallon tank and my 55 gallon tank! but then again I only have 3 plants in e4ach tank, do I need any ferts,? if so the most important ones.