Just for fun......try this perspective. I argue the GT is as rare as the Shelby line. I have had the good fortune of owning each model year Shelby and Boss over the years, plus some other Fast Fords. And boy do I wish I could have kept them all:bored, but to be honest they all drive like poop compared to even a Fox body Mustang.
Approx 13,000 Shelbys from 65-70. ( 1970 were carry over 69's and only 562 cars in 65) So really only 4 years of real production. Slightly Over 3,000 cars per year on the avg.
4,000 GT's from 2005-2006, US production is I believe is 3,700ish. The GT is 3 X as rare, when you look at it from this perspective. You could argue they are all the same though. You could also argue there were only a few real bad boy Shelby's. So lets take a look at the history of one of my old cars that was a non bad boy 69 GT350, yet still a 2 X SAAC gold winner.
the 69 Sold new for about $3,600. During the odd / even gas rationing and rise of the "Pinto" Halo car:thumbsdow it dipped to about $2,900 in 74, I aquired it then, Dad offered me a new V6 Mach1:willy. Ten years later (1979 )it was worth about $5,500. 20 years later (1989) it was worth about $15k, 30 years later (1999) about $45k almost 40 years later 2007 $126k. The market got a bit over heated in the last few years IMO.
You can do the math, but it has gone up more than ten-fold in 30 years. If our cars do half or even 1/4 as well we would all be very happy and so would our heirs.
And a little more trivia:
the Hurst cars were considered beaters and one should stay as far away from them as possible, they were going for less than half the normal 66 at one time. Don't ask how I know. The Boss 429 was considered an odd duck that was impossible to work on or find parts for. The good advise was to stay away...again don't ask how I know. Some good advise I never listened to very well.
If you track the 93 Cobra Mustangs you will find good cars have held their value to window sticker over the years. But it was a one year car with just under 5,000 copies.
The 94,95,96,97,98,99,00,01,02 were all pretty much the same and had over 45,000 copies, thus they are insignificant today.
The 03 is the stand out car in the group, still sought by racers as they are lighter than the 05 and can make equal power to weight ( unique and likely to be a high priced car 30 years from now). They held value well ......
Until the Shelby came out. The 03 was trumped by a newer, faster better looking car. Exactly what many have suggested plays out in the car resale value game. Now this car is trumped by the KR and Super Snake.
Ford would really have to step up to Trump the GT. GM will not do it now and the ZR1 while unique, does not have the BAM factor, the Viper is on it's way out. The new Camaro or Challenger are not threats. I argue we own the last great American Supercar our generation will see. It and the ZR1 are and will be the high water marks for a long time to come.
We all tend to return to our youth at some point. My 26 year old son and his buddies will be remembering the Vipers, Vettes and GT's as the cars that made their jaws drop more than the 60's stuff. I argue they are tomorrows collectors as us baby boomers will be a bit old 20 years from now when they will be in their prime collecting years. I think the next generation say's it everytime you get gas "Gee mister, I am going to get one of those when I grow up".