The cost of a 1970 Dodge Charger RT varies enormously depending on its condition, options, originality, and the current collector car market. A heavily restored, concours-quality example could sell for
hundreds of thousands of dollars, even exceeding
$200,000 or more. On the other hand, a very rough, project car might be available for
$50,000 or less.
There's no single price. To get a realistic estimate, you'd need to look at current listings on sites like Hemmings, Bring a Trailer, ClassicCars.com, and others, and consider the specifics of the individual car you're interested in.