dealsseagate barracuda green st1500dl003 1.5tb 5900…

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4 eggs with 246 reviews.

$99.99 on Amazon with 3 1/2 stars and 167 reviews.

5900RPM and ~4.85 Watts while in use. Claimed sustained rates of 144MB/s (though I find VERY hard to believe).
http://www.seagate.com/internal-hard-drives/desktop-hard-drives/barracuda-green/

According to this article right on Seagate's webpage, and quoting from Dave Burks, Marketing Manager for Seagate, the power savings of their green drives amount to a whopping 40 cents/year.
http://storageeffect.media.seagate.com/2011/11/storage-effect/why-seagate-said-goodbye-to-green-drives/

Leg work, done. :-)