Ask ten collectors what a key should sell for and you will get ten answers. Can these historical prices be used as a guideline. Only if you know the circumstances of the sale . Do you know the condition of the key. Often, the exorbitant price that you hear of was the result of a well shopped key and an over zealous buyer.
Key prices are kind of like TV journalism.
You will not hear about the every day, reasonable deals. You are going to hear about the really big ones. Before you quote historical prices, make sure you are able to quote the circumstances surrounding the sale. This can be rather risky. Most technology collectibles go through a bell shaped popularity curve.