I looked in to growing them myself, to sell not use, but decided against it in the end. At a music festival in August they were sold dried at a tenner for a very few grams - perfectly legally.
The smell of profit was appealing at that sort of price for something so easy to grow on my land, but we couldn't find an outlet that seemed sensible. I was also rather worried about having four spaced out horses hanging round my stables suffering from the munchies!