Not sure you understand what a hard drive enclosure is. When you buy a portable HD you are buying a 2.5" hard drive in a case that you can't (not supposed to open). It's in a permanent hard drive enclosure. You can buy a 2.5" enclosure that's the same size as those portable HD's but usually has 2 screws so that you can open it up and replace the HD. They usually run from about $10 to $20 for the enclosure plus the cost of the HD. If you have a 2.5" drive laying around this would even be a better reason to go that route.