Do you have an external Seagate Hard Drive like this one? If the hard drive dies, you shouldn't throw the whole thing away. Rather than buying a whole new external hard drive, you can save money by opening up that external hard drive and replacing the dead, internal drive with a newer one. Useing the external case and buying a cheaper internal drive will save you some bucks.
You can open the casing, put in a newer, internal drive (if your original external drive was a smaller capacity one, you might have better luck sticking with a similarly small capacity drive due to the power and firmware restrictions you could run into), and reattaching the case. For the full Tutorial, head over to Instructables by MonkeyAgent