Do not let them try to build a Google competitor or something similar. It is unrealistic for them. Have them engage in some kind of e-commerce and use something like PayPal where there is a chance that money will actually come in the door. Have you local newspaper do a story on you and the class participants, maybe following their efforts over time in the Sunday edition.
Form groups of 5 students and have them come up with ideas that you put on a list. When you have 50 money making ideas on the list, break into groups of 2 and let them try to implement the ideas they think will work. If more than one group of 2 chooses the same idea, that is called market competition.
I think they need to learn to bunt, before learning how to hit home runs. If you think they will all hit home runs and work to make no money, I think they will be discouraged and it will be a negative experience for them. Probably not what you want.
Maybe some will discover that this industry is not for them and go on to own a restaurant in your town. I think that the lessons learned can be applied to any business.
I think you should include some examples of companies like Zappos that sells shoes as well as companies that develop and sell software or provide SAS.
Also instead of case studies (that’s a lot for kids to focus on and digest) do PowerPoint lectures and also "make them earn" the privilege of learning how to use PowerPoint to make a Pitch Deck on a special Saturday lecture at the end of the course. But of course they can all attend, it's just a ploy to get them to focus hard on the course work that you can dangle over them during the semester. The carrot works better than the stick.
Also, you should have one lecture about, accounting, taxes and legal entity formations where a CPA comes in and answers questions. Also explain what a Corporation is and why Delaware might be a good choice.