You never think you'll need four terabytes of storage until, well, you do. If you don't mind picking up an external drive, JB Hi-Fi is currently selling a 4TB Western Digital model for $159.
The offer is available online and for walk-ins, with the price around $15-20 cheaper than what you'll find via staticICE at the moment.
A couple of details to keep in mind -- the drive is not USB-powered, so make sure you have a wall outlet free. Also, if you're planning to take the drive out and use it inside your PC or NAS, it's a WD GREEN model with "aggressive" power-saving, which may not be the best choice for the aforementioned applications without a few tweaks.
Otherwise, it's a boatload of megabytes at a competitive price.