That's exactly what we've done! When we moved into our house an 8 x 6 shed was left behind. The felt was ripped off and the windows smashed but it was actually quite an expensive one. It's since been painted inside and out, mesh in windows, new felt and a lino flooring. My husband made a hutch to go into the back with a little hole for both my mini lops to access in and out, we've added some levels and a ramp, shelving for storage and some toys for them (oh and of course a litter tray!!).
Father in law is in the middle of making a run to put on the side of the shed as there are already patio slabs laid.
A shed is great as you don't get wet when it's raining and it's not quite so cold either! Our bunnies love it!