It's kinda hard to say exactly what figure it will drop to in 5 to 7 years time, it varis on a lot of factors.

eg, in AUS, a 99 diablo at 2002 was around 280 to 320 thousand dollars depending on models and since the goverment re-introduce new legislations in late 2003 and no one has the rights to bring in used lamborghinis, and the price has pushed up $40 to $50k for the same car.

for the states i don't think a 99 or above diablo will fall under $130K in 5 years, but somethings you just never know.