Yes you do! You can enable this for any item by going to the Options tab of the item record and turning on "Prompt for price at time of sale".
With this setting enabled, when the item is applied to a ticket at the Point of Sale, you will be prompted to enter a unit price. Once the price is entered you will be able to complete the transaction.
Note: This setting overrides any price already assigned to the item. This means that when you see the item on lists, reports, and elsewhere, the price will show up as blank ( - ).