Who told you they are not coming down??
In Florida land prices in 2008 are in some places 1/5 to 1/4 of their 2005 prices (a 75% reduction).
Same in Arizona, California, Colorado in 2008.
I am even following some Spanish sites with land prices and they have come down by 20% in the last 3 months.
So yes, the price of plots DO come down and comes down hard.