If there are any teachers reading this post: WHY do our schools need money? What are they trying to buy? Does the school really need it? Aside from the fact that schools are either underfunded or aren't budgeting correctly, can we use this money shortfall as teachable moment?
Would it be better to put forth a "problem," such as: hey kids, we need to raise $500 to go on a field trip. Let's come up with some solutions to try to get it. And then facilitate a full-class discussion on different ways to get the money. That way the kids might come up with some creative methods, and take ownership of the issue. Instead of grown-ups telling them that they all have to compete as sales staff. (Is the purpose of this exercise to prime our kids to be better furniture sales staff in the future?)
Maybe one of the solutions might be: "we don't need to go on a field trip to study trees...let's do a walking field trip and study trees right in our own neighborhood." Or, "let's do a study on how much energy we're wasting as a school and figure out ways to save money."
Doesn't answer your question, but I thought I'd bring up a little "outside of the box" perspective.