Bony,
I think you are correct that the GT may appreciate. I do not think Ford made too many to become collectable.
There have been many cars built that do not have the story of the GT and have had moderate-good appreciation over the years.
I will use the Ford (DeTomaso) Pantera for example.(I think this is a very middle of the road example in what could happen to the GT).
http://www.panteraclub.com/pantera.htm
http://www.dealsonwheels.com/search/detail.aspx?id=000027-200608-000007
1)Imported by ford for 4 years '71-'74.
2)Aprox. 5500 imported during those years.
3)Base price $10,000-$12,000.
4)Was built for a total of 25 years.(including the imported by Ford years, which would make the total number of cars available much greater and could have diluted the market).
5)Todays prices: $20,000-$50,000.
The pantera is a fantastic car but never gained the excitement from the public/owners.It is also a hybrid.Italian coach works and American engine, which is said to be the reason the Pantera never became highly collectable.The automobile community could'nt determine if it was Italian or American but,look at the prices they command today, 100%-500% over new.
I'm not expecting anything like this to happen. I believe you will get all the driving thrills you want for 10-15-20 years with at LEAST a money back guarantee and thats not a bad deal! :cheers