Changing the pin adapter is easy. It slips off the end of the old HD, and you slip it straight onto the pins of the new HD, always being cautious not to bend or snap the pins. Following is a pic of what I am talking about with the pin adapter.

The price is definately very low, must be a mistake (usually US200+), but newegg are very reliable so hopefully will honour it, so snap it up quick.
Good luck,
stu