10 or more drops eucalyptus essential oil
Petroleum jelly, petrolatum or soft paraffin dosn't have any scientifically proved medicinal effect, but should not be applied to the inside of the nose due to the risk of lipid pneumonia. Vicks also contains camphor, which is toxic if swallowed or absorbed into the body.
In any case, this is a much cheaper alternative to vicks. To make a salve, one can experiment with beeswax, for a natural substitute.