Hard drives might not be as popular as they once were, but when it comes to storing massive amounts of data cheaply, they're still the best option in town. For those of you looking to store your entire Steam collection offline (or a few installs of Call of Duty), Western Digital has now slashed the price of its 12TB external hard drive to just $174.99. Best of all, you don't even need an Amazon Prime subscription.
This external drive connects to your PC over USB, but requires a separate adapter for power (which is included). It's pre-formatted with NTFS for use with Windows, though you can reformat it to whatever file system you'd like. Customer reviews point to the disk being a 5,400rpm unit, with maximum transfer speeds of around 90-100 MB/s over USB.
WD 12TB Elements Desktop Hard Drive | $174.99 (save $43)
This external hard drive is $43 off the usual price, and you can take the drive out of the enclosure for use inside a PC or NAS. The sale requires a Prime subscription on Amazon, but you can also get the same price from B&H Photo and Newegg.
If you decide later on (or immediately) that you would rather have the drive inside your PC, it's extremely easy to take out the internal SATA drive and place it in your PC. There are various tutorials for this process online, but it usually only involves taking off the plastic shell and unscrewing the drive. Most 12TB internal drives go for around $200-300 (depending on speed), so as strange as it sounds, buying this external drive and fishing out the HDD within is cheaper than just buying a 12TB drive designed for internal use.