I need help to find a correct and affordable university to do a Phd in the field of herpetology?

I did my Mphil research in the field of herpetology on snakes of Northern Region of Ghana where i had over 20 snake species and would like to proceed to do a Phd on snakes and crocodiles. But that experience i cannot get from a developing country like my own Ghana, hence i need advice on how to get a school with excellent herpetological studies..