The economy... of a school

Okay, so there's this thing called market day at my school, where all the fourth graders make something and sell it to other fourth graders, third graders, and fifth graders. I, happening to be in fourth grade, am under pressure to create something to sell. I am going to make origami for twenty-five cents each, and just hope I pull it off with my book report where I can't find the book. So anyway, half the fourth grade is selling on May fourth, and the other half on May sixth. (That's me!) I know I want $10.00 at least, so that's like 46 origami if I pay tithing. It'd leave me with $10.35 so since I need like $70.00 ultimately I'd have to earn about $54.00 since I have $5.48. Still, $54.17 to earn? I'd better get started!