Many people who own Quinny Zapps will have experienced the overbalancing if you try to place anything too heavy on the handles.  I found a perfect solution and it cost next to nothing.  Go to your local sports store or look on ebay for wrist weights, or ankle weights as used by some joggers/walkers, attach to the front wheel frame of your Quinny Zapp and hey presto you can now go shopping with your Quinny - if you want the weight to match buy a can of spray paint to match or co-ordinate with your Zapp and you wont even notice the cuff attached.  These cuffs attach using a thick velcro strip so are easily taken off for cleaning or travelling, still folds with the cuff attached!