yes you can easily buy sites using cms like joomla, wordpress and etc., but blogspot is not a cms , it is a blog tool you can login with blogspot and get your unique url and write blogs. both are different in terms.
I have a script for download youtube ( not the on my sig links ) which is based on wordpress. I reached 3800/day people and growing.
So yes you can buy sites with traffic based on wordpress, joomla or you can make them.