I have to say that I don't think Carreras are all that valuable. Not yet anyway. The economy is just now really showing its downturn and older high end sports cars are not likely to retain value. I think all the writing will be on the wall when the later Carreras reach age 30. Whatever they are worth then, they will always be worth at least that.
However, I will add that the value of the early cars ('65-'73) will pull the rest along. If they continue to soar in price, that will help all 911's, IMHO. At this point, I'd take a wait-and-see approach.
If you want the car, buy it. 15K is not that much for a car these days. And forget all this.
