Despite being stylish, cheap and definitely innovative the Microdrives were -one has to admit- rather shoddy and infamously unreliable and that was exactly the gap the Opus Discovery Disk System aimed to cover. Costing almost 200 pounds, this pretty excellent backup/disk drive thingy wasn't a particularly popular add-on, but it definitely was a very handy solution. And it worked perfectly without eating away at the Speccy's humble RAM. No, really, here's a review.
Happily and due to its obvious retro status you can now grab one for a much more reasonable price via this Spectrum w/ Opus Discovery System auction. Not only will you be getting a fully working disk drive which doubles as a power source, but also a 48k ZX Spectrum, a TV-out cable, a manual and some disks. Seller ships worldwide.