IMO, you are better off having two presses. It has been my experience that there are just some things that need to be done on a single stage press. I personally believe that ANY reloading bench should start with a single stage press. If you want to add a turret press or a progressive, that's fine. What you will quickly find is that the turret and progressive presses are nowhere near as versatile as a single stage press. They can have speed advantages, but you will still encounter situations where you really need a good single stage press.
I will give you an example from my own reloading experience. Recently, I and a good friend of mine began high volume reloading for .308 using my Dillon 650. We were using once-fired military brass and had a large number of cases to prep.
The first thing we used a single stage press for was decapping. We set up my buddy's Lee Classic Cast with a universal decapping die and proceeded to prep several thousand cases.
When we began to load ammo on the progressive, we found out during testing that the cases had not been sized down far enough to chamber in our rifles. We then had to re-process the brass with small base dies to cure the problem. Simple matter, we set up the single stage with the small base sizing die, reprocessed the brass, and continued the process.
In general, I find myself using the single stage most of the time. When I am going to load in small batches, such as when doing load develpment and when assembling match ammo, I use the single stage. When I load for volume, I use the Dillon.
Could you get away with just a turret press? Probably. But, a rock solid single stage press such as the Classic Cast is not expensive (a bit over $100) and is useful to have around. I truly believe you will be surprised at how much you find yourself using the single stage.