Voigtlander doesn't produce their lenses for long. I imagine demand was high and supply low, hence the spike in price. I bet it'll stay that high or go higher unless they make another run of that lens.
Just imagine the deal people got that picked up the Voigtlander 125/2.5 for less than $500 when it came out...simply mindblowing. Too bad Pentax is off their list now (following suit with Zeiss). I love my 58/1.4, and doubt I'll ever let it go.
Now our hopes are on Samyang for new quality manual focus glass (for Pentax at least).