The cars that will bring the money down the road will be Early 84-85 cars, SA-5, SA-10, SA-15, SSC,SC,and SR and nice low mile S-351 cars. I doubt the 99+ cars will bring much since so many cars were produced...
I may have left a few out, but those particular cars stand out to me.
It is more rare but, it isn't hand built like the S-351 and the power output is less. If you look at Shelby prices the ones actually built at Shelby American are the more valuable ones. The S-281 cars will still be worth considerably more than a GT or regular Cobra. In the future the value will start to go up.
I believe the early saleens will do will be the ticket in years to come. As long as the production numbers are low say under a 1000 units. for example look at what the Hemi Cudas sell for 150k+ and there were like 700 +/- units and the Boss 429 cars 859 units in 69 and 1359 in 70 and they sell for 150k+. My 89 is 1 of 7 black converts with a total run of 734 for '89. I always wonder of the 734 how many are left? So we'll see what happens in another 30 yrs.
A little off topic but - I was out looking at this years Barrett-Jackson list and nitised that the 1 and only Bon Speed Saleen Thunderbird is going to be there for sale!!