I haven't seen an amazing deal on external 8s in a minute, but right now I see a new price of $144. Used for ~$100, I'd be looking for a drive with not much over 10k hours in service. I ball park what I'm willing to pay as a ratio of hours used of a nominal 30k hour lifetime. Though I won't pay as much for a used shuck that doesn't come with shell if the warranty hasn't expired. My thresholds don't often line up with the asking market on eBay but I rarely need a drive next day so hit the amazing sales hard when they pop up.
