I make my own...ain't no thing and it cost me less than 3 cents a gallon, including the shipping of the salts.
I would be happy to share the formula I use...or pretty much anyone can come up with something good...it is simply a matter of coming up with ppms for each element then playing around with the different salts to match that formula.
Here is a list of the different ingredients I keep on hand and how many ppms they contribute at 1 gram per gallon:
CaNO3...41N and 48 Ca...grams per gallon
KNO3...36N and 101K
MKP...60P and 75K
MgSO4...25Mg and 33S
K2SO4...110K and 45S
K2SiO3...71K and 140 SiO2
MgNO3...
Met Ca....15.9 (grams per gallon) or 1ml per gallon is 19
Met K...53 or 68 (ml/gal)
The last two are Albion Metalosate products that I use to fine tune ratios. They are liquids with the K being amino complexed and the Ca being amino chelated (the bacteria in my coco love them some aminos to eat). In general I like (ppms) 125-60-250-125-(50-60) N-P-K-Ca-Mg. I reduce the concentration for veg, etc...based on plant size. I also give a little more MKP for the two weeks following stretch.
Simple as can be and anyone can do it. I get all of my ingredients here:
http://customhydronutrients.com/zencart/index.php?main_page=index You can definitely find them elsewhere but he is a friend and has a calculator at the site for anyone to use.
I have a journal over at the Garden's Cure under YosemiteSam...check it out and judge for yourself if it is effective or not.