My students sell scented jar candles every year to pay for our class trip, with any excess funds going toward a foreign trip they’ll take as 11th and 12th graders. This year each student sold at least 6 candles (except for one who didn’t sell any), and one sold 64. A candle business generously makes the candles for us and charges only for the materials.
I’ve never done anything like this, but your students could probably make their own jar candles. You could take orders and set aside an afternoon to fill them. Or you could just buy some at Dollar Tree. 🙂 If 16 students sell an average of 5 candles each at a profit of $5 per candle you’ll get $400, plenty for a decent projector.