I did a quick comparison of prices from DA OG ERA and the modern era
http://www.mustangspecs.com/years/64-65.shtml
170cid 6cyl 1V 101hp (1964½)
260cid 2V V-8 164hp (1964½)
Retail Prices
Standard Convertible: $2,557
Standard Coupe: $2,320
Standard Fastback: $2,533
http://www.in2013dollars.com/1964-dollars-in-2015?amount=2320
$2,320 in 1964 → $17,870.14 in 2016
$2,533 in 1964 → $19,510.80 in 2016
Now let's look at the 2017 model
http://www.ford.com/cars/mustang/trim/v6fastback/
$24,915
Horsepower
300 hp @ 6500 rpm (3.7L V6)
310 hp @ 5500 rpm (2.3L EcoBoost[emoji]174[/emoji], Premium Fuel)
435 hp @ 6500 rpm (5.0L V8, Premium Fuel)
526 hp @ 7,500 rpm (5.2L FPC V8, Premium fuel)
$5-7K more for double the horsepower along with features that make modern cars pretty much like spaceships (including advanced safety and 3x better fuel economy) and Ninjahood is complaining about prices and wanting da OG era of inefficient gas guzzling v8s and riding around in a nylon seated bucket back.