Glad to hear your lesson went well
Role play is always a great idea and is rather engaging for students. For a shopping lesson you could take on the role of a clerk and set up a store using flashcards (you can find tons of flashcards at
Free Printables for Teachers | flashcards, printable games, worksheets templates, phonics materials, ESL printables, conversational activities and
ESL Printables: English worksheets, lesson plans and other resources). Let your students become the shoppers and give them each a budget and a shopping list.
When making the list, you could add a couple items to each list that is not actually at the store. The students should react accordingly, truly taking on the role.
As for what you could throw in....
What did you learn about your students before? Did you find out what sort of shopping they usually do (ie, clothes shopping, groceries, electronics, etc). This could help you build the items for your store. I always want to personalize the experience for my students.
Good luck with this! If you have other questions feel free to contact me.