http://www.seagate.com/ww/v/index.js...001a48090aRCRD
All of the drives I looked at showed a 1.0A spinup current requirement. So you should definitely look for an enclosure with external power. And not some hacky USB power solution either, but an actual thing you plug into the wall.
Taking a quick look at newegg, this is the cheapest one I could find with an external power adapter.
http://www.newegg.com/Product/Produc...-095-_-Product
If you want a dock instead:
http://www.newegg.com/Product/Produc...-031-_-Product