We do not carry any grippers for the Wild Thumper chassis. The manufacturer of the Wild Thumper, Dagu, does carry a version of the Wild Thumper with a gripper that you might look into. They also carry a few gripper assemblies separately.
As far as our shipping costs, you can see an estimate by adding the items you are interested in to your cart and selecting the "Estimate shipping..." option. Please note that this estimate does not include any customs fees that might apply. More information about our ordering and shipping can be found under the "Ordering" tab of our website. You might also check to see if any of our distributors near you carry the items you are interested in.