I saw a thread/poll about how many rpi forum users have and it made me consider why the Osborne effect is wrong.
I could give a long list of reasons I think the afore mentioned effect does not apply to the rpi, but I will just give a few minimal and most important reasons.
1)Computers are now thought of as necessary, disposable(almost), rapidly advancing commodity items, and in the rpi case are so cheap why wait if the saving is so small the wait time value is a far greater loss of opportunity cost.
2)The target market(I wont go further into this unless no one sees, it seems obvious)
It would be interesting to see the sales stats but I guess the rpi models have a fairly long tail?