Remember that any desktop drive will have an expected annual failure rate of over 1% per year. With externals having much higher than that since the cheap external case / power supply they add to an internal drive to make it external tends to be low quality.
********** is an enclosure manufacturer and doesn't sell assembled drives. If you look carefully on just about every ebay entry for them, 1/2 way down the page it says drives not included. In any case, all manufacturers have drive failures. Get yourself an extra drive or two and have multiple generations of backups to be safe.