Not an option for everyone, but I use an old Sun 1 GB harddisk. Has it's own enclosure, power supply and fan. Figure 30-35 watts.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk