Forgive me for this observation, but it appears you are still learning your art. Why commit to spend more money while you are still learning? For example, if you want sharper images, have you chosen the optimum aperture for your lens? Are you using a tripod or a high enough shutter speed to eliminate any camera motion (which looks like unsharpness)? Are you shooting at the lowest possible ISO to avoid noise? Once you have perfected your technique with the gear you have, then evaluate what you lack in equipment and buy that... whether it be a new lens or a new camera. But it seems to me that you want to substitute hardware for experience.