I'm no expert on lenses, but I've heard EVERYWHERE to Get The Best Lens You Can Afford, even if you put it on a cheaper body. You're only as good as your lens.

Remember, sharpening is artificial, and leaves artifacts. You're degrading your image IMO. Best to start with the best image possible.

Besides, even if you could sharpen everything up in Photoshop, is that how you want to be spending your time??