These machines are great little swiss machines, but because they are Swiss they may not be the best to learn CNC programing on. You will need an extensive set of collets and bushing. You might be better off finding an Omniturn or Accuslide. These are Hardinge lathes that are modified to use a CNC X/Z table. They are very common.
The Star SNC15DX is not that common. I have two. One working and one that is not that I bought for parts. If it is a running machine and in very good shape it would be worth 2 to 3 times what the guy is asking for. I suspect it may not be all there or it may have a spindle or servo problem. You also have to worry about the lose of the parameters. Often when they are in storage for any period of time the batteries drain and you could loose the memory.
If you are going to pass on this machine I would like a chance to get it and of course give you a finders fee. If you do want it I can help you through some of the issues you may have when you set it up. I'd like to talk. Feel free to give me a call. Bob at 973-625-7221.