Supermarket has developed a new promotion. For each$30 spend in a single transaction they are randomly given a pack containing a miniature replica of...

Supermarket has developed a new promotion. For each$30 spend in a single transaction they are randomly given a pack containing a miniature replica of a shopping item. there are total 30 different items. how long do you expect me to collect all 30 different items?

(items may be repeatedly received)