I've heard rumours about them opening a shop where these rares are of certain prices - with a limited amount of each rare (estimated from the active rares in August 2010).
This leaving the first people to get to a worth-while cash pile able to buy the rares - the harder each player works the more rares they can get their hands on, knowing their investments are worthwhile as the rares will be worth more in future.
This seems like the most logical answer in my opinion.
I for one will defo be trying to buy as many of these as I can haha.

















