I have a $125 set up and am able to pull close to 2 ounces a plant of dense...dank bud.
It's something that you are doing wrong. You need to keep it simple. Try and remember that you are growing a fucking weed...not cloning George Washington and splicing his genes with a laser wielding shark.
In the wild...weed is not fawned over. Yes you are trying to give your girls ideal conditions...but even just "better" than they'd see in the wild can be plenty good enough. Good genetics, good soil (do not be a chump and spend a gazillion bucks on dirt...I spent $8 ) and the proper fertilizers. (again do not be a chump and spend a lot of money...blood meal, molasses and miracle grow 15 - 30 - 15 powder is what I use...grand total? about $17)
Being a bit light on the water is superior to being a bit heavy. Same thing with nutrients/fertilizer. They will not die with 1/2 doses...but may die if you give them double doses.