I don't know, after all its a matter of time for a beta card to be equal to an alpha card. Let's see what happens, this will be a wonderful experiment because we hadn't online market when MTG was played for the first time.
Never it's been so easy to buy or sell a card, it's exciting.
It's a matter of time, but a long time :).
Think about this, if the prices of the betas are way lower, then they will be very easy to max with beta copies. Then the beta will sell faster than the alpha.