If you have a quality aluminum frame bike, it probably has a carbon fork. If you find the ride harsh, you'll get most of the benefit of a carbon frame by swapping in a carbon seat post, stem, and bars. There are plenty of good, moderately priced carbon parts available, and changing these parts is very simple. If you are on 23mm tires, change them for 28mm, which will fit in almost all rim brakes.
On lo-end carbon frame bikes you will find alloy bars and seat posts, which is silly.
On lo-end carbon frame bikes you will find alloy bars and seat posts, which is silly.