This project is no small undertaking, but if you’d like a greenhouse for a lot less than you might normally pay, and which uses a lot of recycled material, this may be the thing for you.
Made from recycled windows, you will need tools, lumber and a few other things to create this, but how woudl you not feel like your name was Clever Clogs if you had one of these in your back yard. See the step-by-step for this at Instructables.