"If prices don't come off 40% back to the trend/support"
What trend/support are you talking about bassyabbie? Can you provide a chart, more detail, link to data? In what specific metric/measurement are houses overvalued by this amount?
"when was the last time anything went up 40% and kept its gains"
In real or nominal terms? Measured in/against what? Plenty of asset prices have risen 40% in the past and kept their gains in nominal $ terms.
Don't get me wrong bassyabbie, I don't think prices are going anywhere but down over the next few years, however it's best we argue the case with facts & figures and draw conclusions from these rather than posting opinion pieces.
