Amazon offers the Bell Kids' Doc McStuffins Protective Gear Set for $6.52. Add it to your cart via Subscribe & Save to cut it to $6.19. With free shipping, that's the lowest price we could find by $12. It includes kneepads, elbow pads, and gloves.
Be sure to cancel Subscribe & Save after your order ships to avoid being billed for subsequent shipments.
It has very good reviews on over 50 verified purchases at Amazon.