Textbox currency format.

I have TextBox witch accepting user input as price.

i want when user put price it should be display this format 10000.00

XAML:

<TextBox Height="23" HorizontalAlignment="Left" Margin="109,284,0,0" Name="txtprice1" VerticalAlignment="Top" Width="136" RenderTransformOrigin="0.738,2.115" />

Please guide me.