@Eternalturnofthewheel, in most cases the result of an overvoltage from a 19V laptop adapter is a shorted 12V TVS diode. The solution in most cases is to simply remove the diode with flush cutters. This will cost you nothing, except the price of a Torx 6 screwdriver.
... and http://www.users.on.net/
~fzabkar/HDD/ (photo clips)
If the board has sustained additional damage, then the most you will need to pay to replace it, including a firmware transfer, would be about US$50.
A firmware transfer is required because most modern HDDs store unique, drive specific "adaptive" information in a serial EEPROM chip. This chip, or its contents, needs to be transferred from patient to donor.
The following PCB suppliers offer a firmware transfer service, either for free, or for US$10: http://www.donordrives.com http://www.onepcbsolution.com http://www.hdd-parts.com