We need to wait a bit to see which way the market is going from that range. My bet is on up, of course, based on the fact that we've reached the price level which the Bitcoin economy can sustain based on the transaction count, and on top of that the value of all Bitcoins, which at $5 is 35 million USD, is a believable number for the current value of the whole economy.
The value thing is simple common sense thinking and trying to get a range for the value of everything happening in the economy. Is it hundreds of millions? No. Is it just a couple of million? No. Is it tens of millions? Sounds right to me. This is what my common sense tells me, feel free to disagree though.