To start your own town you have to save up enough money to get Mayor. The Resident rank costs $15,000, and will let you become the co-mayor of a town, but to create your own town, you have to get Mayor afterwards, which costs $85,000.

 

You can technically be a "mayor" of a town at resident. You would be able to add members, not owners so you could have an active co-mayor that is Mayor+ to add owners. Since you are resident you could have not applied for a town, hence the town will not be yours so you can't get a portal or any other town features. Unless the person that sold it to you is inactive, you could pay the original owner 75k for a town portal and he/she could buy it.