How To Add Event Handler For Property Change Of List Item

I have a class called solution. This class has a property named cost. I also have a class called solutionList that inherits List(Of Solution). I have an instance of the solutionList class in another class called solutionGroup. Within the solutionGroup class I have a property called totalCost that sums the solution.cost property for all solutions in the solutionList.

But, I need a way to know when the cost has changed so that I can recalculate the solutionGroup.totalCost. I've added events to the methods that add or remove solutions from the list but I need a way to know if someone does something like
SolutionList.Item(0).cost = 100.
How to raise an event when the cost property of a solution that is in the solutionList is changed but with no luck.

Here is my solutionList class:
Public Class solutionList
Inherits List(Of Solution)
Friend Event listChanged(ByVal sender As Object, ByVal e As EventArgs)
Public Sub New()
End Sub
[Code] .....