One way you could go is to buy or build something along the lines of a storage building. Let's say 16'x24' and see how that works out. It's not so big to cost you allot for heating and cooling but gives you some room for the machines you want and then some. If you outgrow it you can use it for something else and build a bigger shop.
One thing I suggest is that if you buy a good knee type mill you'll have little need of a drill press.
