Not a bad hard drive, just a bad cable
I thought my hard drive had died. I was getting the international "no" symbol at startup, then a folder with a question mark in it. I bought a new hard dirve and installed it, but still no luck. This is when I thought it could be the cable. Turns out it was!
The process was fairly simple, since I had already replaced the hard drive. I just had to take it a few steps further to replace the cable. Works like a charm now!
If you think you have a malfunctioning hard drive, consider the cable. Especially with these models of Macbook Pros. Looks like other people have experienced it too.