I utilize a simulation in my senior business classes that I think could also be useful in a mathematics classroom in the lower grades.
Junior Achievement Titan is a business simulation where your company creates and markets a fictional product. You are given a lot of control over how many parameters you want your students to be able to control depending on their level of understanding. The resource is free to use and a representative from Junior Achievement will spend about an hour with you on the phone walking you through how the simulation works and strategies to implement in your classroom.
I hope this helps!