assign the value of the selected parameter

I am trying that when selecting an option of the dropdownlist , I see in the cost field the price of the selected thing.

  

For example, if in the list I select "Simple". In the cost field   "800" appears and if I select "Double" in the field cost   "1200" appears.

This is my html code:

<ion-item>
<ion-label>Tipo Habitacion:</ion-label>
<ion-select [(ngModel)]="userData.tipo_habitacion">
  <ion-option value="Sencilla">Sencilla</ion-option>
  <ion-option value="Doble">Doble</ion-option>
  <ion-option value="triple">Triple</ion-option>
  </ion-select>
</ion-item>