<DataGridTextColumn Header="Name" binding={wont work in here as this element is bounded to the itemsource of the DataGrid} IsReadOnly="True" Width="150">
                <DataGridTextColumn.ElementStyle>
                    <Style TargetType="TextBlock">
                        <Setter Property="Text"
                        Value="{Binding DataContext.CustomerCollection.Name}"></Setter>
                    </Style>
                </DataGridTextColumn.ElementStyle>
            </DataGridTextColumn>

<DataGrid.Resources>
            <l:BindingProxy x:Key="proxy" Data="{Binding}" />
        </DataGrid.Resources>

                <DataGridTextColumn.ElementStyle>
                    <Style TargetType="TextBlock">
                        <Setter Property="Text"
                        Value="{Binding Data.Name, Source={StaticResource proxy}}"></Setter>
                    </Style>
                </DataGridTextColumn.ElementStyle>