Location pays a big part in pricing.
A nice SC listed for sale at a Major Metropolitan city will have a lot more potential buyers that are close buy to look at the car and their income is higher.
If you are smack in the middle of swamps you have a limited pool of buyers
I would not travel further then 500 miles to look at a an SC or Carrera unless it is a unique, a very good deal or an exceptional example to justify my time and travel expenses.
One ting that puzzles me is that if you purchase a nice SC for $11,000 and a year later you find out that the motor will need head studs and then you know have a $16,000 SC where as sometimes you can find one with the top-end rebuilt for 13-14,000 and you are ahead of the game.
IMO, I think the prices for the SC's will remain flat for a while and the clean, non-modified examples will start to go up in value probably within the next 5 years.
Hope I did not ramble too much (Strong Coffee)
