Although macs tend to be more expensive, for kids it is the perfect choice- no dealing with viruses, adware, spyware, crashes....they just run and they run well. They have a mac mini- just the computer, you add your own monitor and keyboard. That would be one of the cheaper options if you go mac. Very easy to use too. We've had ours for 7 years and it runs great- just added some RAM and an extra hard drive.
Jackie