Hi all, I have a Macbook pro, early 2011 (antiglare screen), with 4gb of Ram, a 2.2 ghz i7 processor, and a 750gb hard drive. Due to a recurrent issue in the model, the logic board etc. was replaced in June 2015 (i'm sure this issue and fix is familiar to some of you), and this week a new battery has been fitted. The hard drive, however, is still the original one, so probably could use upgrading. Does anybody have any idea how much this would be worth? Thanks!