I love my panniers, though they aren't that aesthetically appealing they function really well. What I like about them is that they easily clip on to the bike rack, have a strap and a handle and are open at the top which makes them perfect for shopping. Simply lift them off the rack and take them into the store and fill them up. I balked at the price but eventually bought them a few years ago and they are holding up really well. Maybe you could find something similar on Craig's list or amazon.
The ones you linked to are attractive but I think they may be a little difficult to use. Looks like you would leave them on the bike and then bring the bagged groceries to the bike.