If it costs you 5 pounds an ounce, then your power costs are either orders of magnitude lower, or you're getting 10g/w. My power bill is $150-200 a month and I'm averaging probably 3oz a month. Are you stealing power or growing outdoors? Those are the only options for growing so cheaply where I am.
I am not incompetent. From what I've read I may actually be the first person to beat root aphids without killing all their plants and starting over. I managed to take a grow everyone said was doomed and actually produce some quality product (root aphids always, ALWAYS come back with the methods for control suggested online, and they trash a plant fast, worse than mites). Here's a nug:
As I said I don't even sell. I only grow for my own needs. I don't like anyone knowing what I am doing, which selling would necessarily entail, I don't like worrying about getting robbed, raided by cops that don't know I'm legal, etc. I am stepping in here because I think you are completely wrong on the real cost of growing...
Still don't understand how the risk of prison doesn't factor into your price calculations. You're in the UK, you have no legal excuse, I'm at least doing it legally. You're the one risking prison here. This should be very real to you. Either you're trolling or you're just plain stupid...
Oh, and as far as RO filters go, it's not "as expensive as you like." Where I live they are NOT optional. My tap water will kill plants. It's loaded with copper.