There are two buttons to order with. One is at the top, weighing in at less than 2 KB. The second is at the bottom, at 7 KB.
Both images load very quickly. The difference in load time between the 2 KB button and a stylized text link is negligable. We're talking tiny fractions of a second.
Anyone coming to the page is likely to read at least some of the page before clicking to order. If people placed orders the second an "Order Now" link/button appeared, we'd all be a lot richer
