How much does a computer hard drive cost?

It varies, the more space you want the higher the cost. I recently baught a new HDD for my computer and it ran for about 325 dollars, for a fairly large HDD. Answer As the above poster has mentioned. Costs do vary, from country to country, and size of drive required. You can purchase used ones, from as little as £1.00 for smaller 4.3gb and less..
Hope this helps cadishead computers