I use FFOF... and Like DemonTrich, I can find it for $13 a bag and sometimes as low as $10 a bag.
When you mix it 1/3 with perlite it really goes a long way. I also add 1 TBSP of lime per gallon.
Now... the cool thing is, I start my seedlings in 1 gallon pots, they get no nutes as the soil has plenty. When I transplant them to my 5 gallon containers, once again the nutes in the FFOF mix is enough to feed them for another 2 - 3 weeks. So I'm 6 - 8 weeks before I feed them any nutes. Then its only 1/2 strength to get a read on how much the girls want/need.
So, the way I look at it, you can put out a few extra dollars for your soil, or pay considerably more in nutes.
Just my 2 cents....
Good luck and keep us posted.