Since this is a candidate-led case, the candidate should drive the case from start to finish.
A local sandwich place has a shop located in a busy business district. The business district is filled with large head-offices of major corporations, a train station & a university. The sandwich place only sells one type of sandwich priced at $5.00. This is a cold-cut salmon sandwich with bread, smoked salmon, salad, cheese & sauce. The sandwiches are freshly made and only prepared after the order is placed, so no pre-packaged sandwiches. The shop has 3 employees who all service customers and it is a take-away without any seating.
Try to estimate the total revenue this shop can generate in one month. Costs are no factor here. Try to base your estimation on logical & reasonable assumptions that would be common for a sandwich place as described here.