"Is" is the verb of this sentence. Though a subject of a clause is typically in front of the verb, this is an "inverted sentence," meaning that the subject comes after the verb. If this sentence weren't to be inverted it would read, "The price of a movie (is,are) eight dollars these days." The verb is describing the word "price" and because "price" is singular, it must have a singular verb meaning the correct verb usage is "is."
