Pat here's a demo of using reatune in reaper. It might give you some ideas. If you notice in the video, he's correcting to exact pitch, which works well in that context because he's working with harmonies. But for a single vocal, you can vary the line and
move in and out of pitch. In other words, just make it a better singer but not a perfect singer lol.

Reaper is a free download and not hampered in any way so you could play around with it some if you wanted. If your needs are fairly simple, it may do the trick.

For what it's worth, and as near as I can tell, melodyne crashes in every daw I read about, BUT, just about everybody says it's still worth it lol. Of course, they're working on it all the time, and they're (melodyne) supposed to be working on a standard that will be made available to daw makers sometime soon.

https://www.youtube.com/watch?v=lJpjZtgPR_g&feature=player_embedded