We are primarily a Windows family - we have no experience with the Mac OS. I have a 4th grader who is very interested in learning computer programming. He has been watching videos online and is developing a website on his own . Of late, he had been pestering me about buying a Mac. He wants to develop for iOS using Xcode. I'm looking for a cheap Mac that can run El Captain. Any suggestions on what would be a good fit? Doesn't matter what year/model.