How much should I sell my php template for?

Hello webmasters,

I want to start selling templates, but I don't know how much to ask for. I want to be reasonable and not sell myself short. Here is an example of two of my scripts:

1. https://farrisblog.farrisfahad.com/
   
2. http://farrisdirectory.farrisfahad.com/

I want to count the advertising cost because if I want to sell I need visitors.

I was thinking $99

Do you think it's fair?

I am currently selling it for $15 but I am using a marketplace...

How much should I sell my php template for? WordPress ...