Errr... What do you mean by "easily affordable"? A quick look on Amazon says that I'd be paying something like €18.80/TB, so buying 400TB would be €7,520 - far out of the range of the majority of hobbyists. Plus a 100GBE NIC would be another €800 or so, plus you'll need all the other ancillary things like a case and a processor and RAM and cabling and whatever the monthly cost to host it somewhere, unless your ISP gives you a 100Gbps connection (which I'm sure will be extortionately expensive if they do). End result is the hardware costs alone approaching €10,000 - significantly more if you want any sort of redundancy or backups (or are you planning to run the whole thing in RAID0 YOLO mode?), plus probably low-hundreds per month, not including the time investment needed to maintain it.