The essential requires a Power supply....whereas sarincv wants a HDD without a power supply...
The only option then would be either:
1. Western Digital Passport 1 TB @ 9.5K approx (3yr. warranty), or,
2. Seagate Freeagent Go 1 TB @ 9.2 K (5 Yr warranty) approx..
The other ones available are Iomega/Imation but I would not recommend any of them...
