I got mine from the local store here, it's an investment to start up but it lasts a while, like I said earlier it's really concentrated. I have all the supplements and the Coco, Aqua Flakes, and I like it. Roots Excellerator is expensive and isn't needed but really when you do the math it's not bad at all, 1ML per gallon so it has 250 gallons worth in it. Also if you do go that route get the Aqua Flakes and not the Hydro, AF is for recirculating or anything that isn't drain to waste.
But if you want to save money, since you have the Botanicare stuff why not just get the rest and use that. GH might even be good for you.