Review on SinLoon 2.5'' Hard Disk Drive SATA 22Pin to eSATA Data USB Powered Cable Adapter for SSD UASP SATA IIIEC-SSHD(Black) - Top Performance & Compatibility by Pascal Santos

Have successfully used this to power some 2.5" Seagate SATAII "Momentus" drives through the eSATAp port on mine HP EliteBook 8470p powered. The only annoyance I've had so far is that it doesn't seem to actually use the eSATAp 5V pins, instead requiring you to add a USB connector. (In my case, this was annoying as the only USB port available for the eSATAp connection was the always-on "charging" port, so the drive would stay on and make spin-up noises from time to time , even when the OS was in hibernate mode.) [I haven't tried it with 3.5"/12V drives on a full-fledged PC yet]