Seagate has announced a 2.5 inch 5 TB hard disk for $85. That's only $17 per terabyte. Is that crazy cheap or what? Seagate's new 5TB BarraCuda ST5000 hard drive is the largest 2.5-inch hard drive yet. Seagate also announced a new $55 7mm thick BarraCuda ST2000LM015, which is the typical size for laptops. Unfortunately, the drive is only 2 TB.