Plugin to charge for text - Chr x variable

I need a plugin for woocommerce that works in the following way.

  1. Customer enters text.
  2. Plugin counts characters minus spaces
  3. Plugin calculates price on formula - character count x variable - the variable should be set in the admin area.
  4. Price updated on the page.

Example use

Customer enters text and is charged based on the font size (variable) of the text.

If you have this option in your plugin / theme or if you can write one contact me.