It's all about gaming...
Growing up I couldn't get enough of playing Monopoly. It was my first taste to learn about investments and negotiations. It was also the easiest way to learn (and fail a few times) because no real money was involved. It taught me about diversifying my portfolio since it is never smart to blindly buy properties on just any color group. I also learnt that it took more than a lucky dice roll to become a winner. In short, it taught me a little about the realities of life.
As I entered high school, I was challenged with a project where we were given a limited set of resources and some capital (fake money) to start our own business with a team. We had to negotiate with local vendors and businesses to kick off our business, provide incentives to our customers and think of ways to maximize our capital (while minimizing our spendings). We had to think about making profits, borrowing money from banks, paying interest and all other fun stuff. It was a good simulation of what it takes to run a small business.
If we can extrapolate ideas from such board games and financial camps/simulations, we can instill both the knowledge of entrepreneurship and finance to students. It could be a week long or even a semester long activity. You can make it more challenging by competing against other schools or teams. Investment in such projects is minimal but the payout is huge!