This also means it has to be in pretty close proximity to the host machine. No connectivity over Ethernet or wifi... Not to mention you have to have (or buy)

This also means it has to be in pretty close proximity to the host machine. No connectivity over Ethernet or wifi... Not to mention you have to have (or buy) the keyboard, monitor and mouse. Some people may have an extra keyboard or two kicking around, not sure how many people keep extra monitors handy for very long (though you can come by monitors cheap on craigslist).