picolo, TonyT, there are VERY precise statistics of exactly this (just not by "person", only by "bitcoin"). All of the data is in the block chain. Anyone can see precisely when every bitcoin was last transferred. There are also pretty good data on exchange rates to whatever your favorite currency is (if not bitcoin). Every UTXO exists in a timestamped block.
Ratcliff has put together some nice area charts showing the age.
http://www.reddit.com/r/Bitcoin/comments/2n205b/an_area_chart_showing_the_distribution_of/So to answer your question, most bitcoin were last transferred at well under the current price.
Note that the most recent transaction may not be when the coins last changed hands.
If the price had been increasing all the time, the output amount X in an UTXO times the price P(t) at that time would be only an upper bound to the purchase price of those coins. However, because of the subtantial drops in price, and the large trade volumes during price drops, not even that is true. Moreover, coins that are deposited on the exchanges are changing hands without a corresponding record in the blockchain.