In economics, <em>scarcity</em><em></em>represents the phenomenon of <em>limitless</em><em>wants</em> suppressed by <em>limited</em><em> </em><em>resources</em>.
In this case, Allie feels she needs $90 shoes while she has not got the resources required to buy them.
This typical economic problem can be solved by moderatingone'swants and clearly identifying what is priority from what is not, then intelligently making decisions on what available resources should be spent.