Simple shopping list
Not difficult at all. It depends on what you want this list to do after, it can be as simple as just adding a field to the existing section.
You mentioned that you want to generate a list from the database to print or email. You probably just need to add a new checkbox field "favorite" to the section and have a script to get all the ones that are checked.
If you still have questions or need support on it, feel free to respond us!
Hope this gets you started and solve your problem. If you need further support or want us to set it up for you. Feel free to send a request to firstname.lastname@example.org.