If for some reason extra costs need to be added to an order use this ADD TO CART button. 1 added to the QTY box is worth £1.00 +tax so you need to add the correct multiples to the QTY so you reach the costs that needs to be added.
EXAMPLE: £100 = 100 qty of the button and so on.
There is also a text box to write what the cost is for so it appears on your invoice.