a mazda5 specific OEM leather MANUAL shift knob is available... it is equiped in some overseas models and is possible to get here from a US dealer... the styling design is basically the same as the plastic one except it is in leather
part number is CC33-46-030 and retails for about $205
for automatics, same story... some overseas models got the leather one... the styling design is also the same as the plastic version... part number is C243-46-030A and retails for about $252
as for a MANUAL mazda3 stock shift knob (not the colored accessories you find in the accessory catalog): part number is BP4L-46-030A and retails for about $215