There are the higher end programs as mentioned by someone else but I have a couple of clients using Station Play List Creator Pro. They have different versions that start at about $65 with the full featured pro level about $300. The thing that I especially like about it is that it will scan designated folders for music cuts and then schedule them based on your criteria and their metadata.
Is it as flexible as Selector or Natural Music? No. But it will generate a simple playlist based on your criteria.
I am not associated with SPL in any way but find their simple, very reasonably priced automation products very handy in certain situations.