Me and my dad built a shed on his plot once, from wood taken from a large collapsed shed, and two old wooden front doors banged sideways onto a frame, on top of the ground. We even reused nails where we could, hammering them straight and knocking them in. The roof was made of sheets of corrugated metal salvaged from old hospital beds.
It weighs so much it hasn't moved an inch in 13 years despite being on an exposed windy site on a hill in Yorkshire... build your own and to heck with the rules, it might not look the prettiest shed on the site but it will be yours.