What he has there is a stripe that has been painted on with a modern "flip-flop" two tone paint. These paints change color depending on what angle you look at them.
Challengers did not come with a stripe painted like that.
You could order an adhesive stripe decal in black or white that looked a lot like that but it is more narrow.
Check this out for the value of this car in the USA. If it has a 4-speed manual transmission, add 10%. I have no idea what Challengers go for across the pond, but that car had better be in perfect condition and really numbers-matching to pull $26000 USD.
Value (for the sake of insurance) is a reflection of what they sell for in the USA PLUS what it would cost for you to import one if you had to replace the car after an accident or fire or something. The chances of finding one the same spec already over here are slim to say the least.
What they sell for is normally just below this insurance figure. Obviously what it costs to import a car varies from country to country in both shipping costs and taxes applied.
I can tell you what they cost to ship into the UK. About 20% over the USA sale price.