Gx Moto racer power booster starter set £3.99 @ Home bargains.
They are £9.97 @Tesco and £11.48 @ Amazon. You can get different ones. Ive found a picture of one design @ amazon, the link is below, so that you can see what it is. Set includes 1x motorcycle, 1x rider, 1x power booster, 1x rip cord.