If you really mean "top dollar" there is a guy who is selling one on e-bay. $80 starting bid, $110 BIN. This is pretty expensive, if you ask me. About a year ago there was a guy selling them for $50. That also was expensive, IMHO.
If this is the part you are talking about, it is the assembly that includes the battery contacts (a chronic failure item due to leaky batteries). Alternatively, there are often options to repair it. If interested in that, I can usually repair the assembly for $25 plus shipping.
Here are two photos of I/O assemblies that I have repaired in the past. The both work fine now.
Here is the e-bay link for the new one if you are interested.
Click here