How big is your shed?How big are he intended projects?How thick will the mdf be?How long are you willing to wait for the parts to be machined?
There are tiny machines on ebay for a couple of hundred-but they won't have the power to do much more than tickle the surface.Or you can get lucky and find an older industrial machine with an old controller within your budget.There are also some fairly flimsy and poorly engineered kits for beginners that might struggle to produce much.Do you have the CAD/CAM software to generate the programs?