To promote the concept of a level playing field, DI places a restriction on the cost of each team's solution.  You will find this limit listed early in the challenge document.

The cost restriction applies to materials the team actually uses in their presentation.  Materials that aren't a part of the final solution and tools used to create the solution but left at home do not need to be included on the Expense Report.

The team's Expense Report (sample) is where a team documents what they spent on the materials being used.

There are some creative rules that can used to price materials.  They include:

  • there is an extensive list of items that are cost exempt that one would commonly find in a school environment such as tables and chairs, audio/visual equipment, computers,...
  • the clothing the kids wear unless it is explicitly styled to enhance the solution
  • a day rental price can replace the cost of an expensive tool
  • if you use only a portion of material purchased (eg 20% of a piece of plywood), only the price of the portion needs to be included
  • yard sale prices can be used for discarded items

One of the jobs that falls to the prep appraiser is to review the Expense Report to see that it is reasonable.  It is normally quite straightforward to spot a team that is trying too hard to remain under the limit.