My practice has been to order an empty external enclosure from Other World Computing then install the drive mechanism of my choice — usually Hitachi (which I also get from OWC). That is the only way I have found of guaranteeing the manufacturer of the drive itself. Besides, pre-mounted drives generally have only a one or two year warranty while purchasing the components separately you can often get up to five years warranty. Go figure!
Installing the drive in the enclosure is easily within the capability of just about anyone who has a small phillips screwdriver (P1) and can read and will follow the most basic level of instructions. My main difficulty has been in handling the very small machine screws without dropping them resulting in digging through the dust bunnies under the desk.
