Hola Ruth
Actually both cuántos (the cuánto used in this lesson and the cuánto in the interrogative sentence ¿cuánto cuesta? have the same intonation in the word cuánto. You can see that they both have the accent on the -ú. The intonation in the sentence however would be different. Exclamatory sentences like these in the lesson will have a different intonation to the interrogative sentences with cuánto.
Saludos
Inma