another gridview question (temporary storage??)

Question

Preview

heres my interface.

http://i279.photobucket.com/albums/kk137/wh3resmycar/gridview.jpg

i can already extract serial column on my gridview and post it on the label (on this example its the label besides the button). now what i want to do after is after the user clicks the button "add product to invoice" i want to extract the whole selected row information and put it on a temporary table like some sort of a "cart" with emphasis on calculating the total price.

how do i display it?