As long as you keep the major essentials such as nutrients, air, and light, any shelter should do. As ganjagoddes said, get a bunch of 2x4's frame your self a 10x5x7 shelter... board it up with plywood and get some siding and nail it on. I doubt it will cost more than 100 bucks. If you need some drawings PM me i can do a quick render for you, im a current arch student maybe i can also get a u quick estimate of what it would cost you