Western Digital and Seagate both have had 2TB external drives for some time now, and Seagate just released their 3TB drive. The new 3TB unit is USB2.0, but has a Goflex module you can swap out for USB3.0 or Firewire 800. Check 'em out
Buy quality dude. I've never heard of Cavalry either, and who knows what's in that thing. I can't even find a 7.2K 2TB drive for under $130, let alone $115 for that external unit. For $109 you can get a 2TB drive and can surely find a cool case for it for about $40, and then know exactly what it's got.