I personally believe we're at a low point for Viper value, and it should go up from here. My thinking is as follows:
1) The body is something dreams are made of - no other car was made before quite like it or will be again, quite like it. This is one of the reasons (while not in the same ballpark) old Mercedes-Benz 540K's are so tremendously valuable - automotive art that was rare and will never have a comparison again in the future.
1a) I don't think the modern pony cars personify American Muscle and even capture the essence of the early classic muscle cars quite like this car. This is a way to get a modern car from the "good old days" and still have something rare/special.
2) They were not high production run cars. From other threads on this forum, you can see that especially when broken down by color and year - each specimen of a Viper is a rare thing.
3) I have a knack for selling things right before they become valuable, and I just sold mine . . . history should tell the rest of you these are about to skyrocket. ;-)
On a side note, I ended up buying my 1999 in early 2007 for $50,500.00 (retail, and for which I feel I overpaid). I ended up trading it wholesale 5 years later for $40,000 even. The value of this car changed very little, and if anything . . . the economy got worse since early 2007 was essentially at the high.
My favorites are the 1996 Blue/Whites (possibly because I had posters of them as a teenager) and the 1999 GTS's (last year of the forged engine) - in my mind, those will be very desirable cars down the road.
-Vivek (lilviv)
http://personal.lilviv.com/motoring/toys/viper-gts.html