Bought from goHardDrive. I've already had a drive fail and require replacement, and that was with pretty much no use. It just failed on a smart test. The same drive, maybe, has already failed again. I'm going to nag em because of the warranty, but it's pretty worrying. Like, I'm sure failing a scrub isn't the end of the world, but it's also not a good thing, right?
If you do buy refurbished drives, ideally get manufacturer refurbished ones that come with a manufacturer warranty. If you're in the USA, ServerPartDeals is a great store for it.
Manufacturer refurbished drives tend to be pretty reliable because they've been tested to meet the manufacturer's specs, usually including a deep stress test, and come with a warranty from the manufacturer.
The thing that sucks at the moment is that refurbished drives cost more than the new ones used to cost.