Try this
Code:
Public Class Form1

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        ListBox1.Items.Add("U-Ad ($350)")
        ListBox1.Items.Add("Striker ($190)")
        ListBox1.Items.Add("New Ad ($250)")
        ListBox1.Items.Add("Samson ($530)")
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim v As Decimal

        ListBox2.Items.Add(ListBox1.SelectedItem)
        Decimal.TryParse(TextBox1.Text, v)

        v += GetMoney(ListBox1.SelectedItem)
        TextBox1.Text = v.ToString
    End Sub

    Private Function GetMoney(ByVal strValue As String) As Decimal
        Dim a As Integer = strValue.IndexOf("($")
        Dim b As Integer = strValue.IndexOf(")")
        Dim v As String = strValue.Substring(a + 2, b - a - 2)
        Dim r As Decimal

        Decimal.TryParse(v, r)

        Return r
    End Function
End Class