Just got a new 13" air with 256GB which I'm thrilled with. This is my first personal mac so I'm still new to some things. What advice do you have for an external hard drive for exclusively using time machine backups? I don't need anything fancy just something to have in case I mess up my new mac I looked at the apple time capsule but that seemed too expensive for me. Is there a cheaper alternative that takes advantage of usb3 or thunderbolt that will work well with time machine? Preferably under $100. Thanks!