iMac HD dead? Best way to fix it?

If you don't feel like reading the whole story just jump to the bottom of the long paragraph for the questions.

OK so last night I was up late watching EyeTV on my 17" 2.0 C2D iMac, it froze and I had to do a hard shut down. When it came back up it booted from my external HD that had a clone of my MacBook HD instead of the internal HD, I restarted again and it booted from the internal. Repaired disk permissions and verified the disk and it said there was an error, shortly after that it froze again, before I got a chance to back up my iMac hard drive (I only have 1 external drive and it's the 250GB HD I use to store my 215GB clone for my MacBook) So after waiting about 15 minutes to become unstuck it did, but immediately froze again so I had to do another hard shut down, I had since disconnected the external HD from the iMac and this time when I tried to start it I got the folder with the question mark, tried 3 times and kept getting this, so I hooked up my external again and booted using the MacBook clone, it's working just fine like this and luckily I use my MacBook as my main computer and use my iMac to just basically watch eyetv/hulu and what not so I didn't lose any data except my recorded shows on eyetv (and I hadn't even watched the newly recorded episode of It's Always Sunny in Philadelphia )

So basically I'm pretty sure the internal HD on my iMac is dead, which sucks cause I was planning on selling it in January to buy a refurbished 20" iMac. So before I sell it I want to fix the internal HD. Does anyone know how much the Apple Store would charge to replace it? can I buy the HD online and give it to them to have them switch it out or would I have to buy the HD from Apple?

Also right now the internal HD isn't even being detected by the SATA bus (according to system profiler) and therefore I have no way to mount it, I don't have a FW400-FW400 cord right now but does anyone think Target Disk Mode would help recover the HD or at least the recorded shows on it, or should I not even waste the money on the FW cord and just count the shows as gone and replace the internal HD?

Any help would be greatly appreciated.

Catch Them said:

BTW is your computer still covered under AppleCare?
If so then they should be able to replace the drive no cost - and get you your content of that drive back.

if not...im not 100% of the price...but they will gladly do it for you no problem, they shouldnt really charge that much if you have the drive in hand and dont need them to install the OS for you.

Click to expand...

No it's not still under warranty, but I'll probably ask them next week how much they would charge, I have to take my MB in anyway cause I've got cracking on the palm rest and my MB is still under warranty.

EDIT-if it's more than $100 for them to swap out the drives I'll probably just do it myself, I was just trying to get a rough idea of how much they would charge to do something like that since I'll be selling the computer to a friend I want it to be done as professionally as possible so it isn't my fault if it messes up shortly after selling it.