That extension changes price into your text.

Set price to 0, then you will see an empty field after price box, there you can add your custom text.
If you want to set global just go to setting -> edit store -> options tab -> stock there you will see new text field

demo to see (product - iPhone or Galaxy Tab): http://oc.gone.lt

installiation guide you'll find inside package.

- no price text on:
+ Compare page
+ Brands / Manufacturer page
+ Search page
+ Special page
+ Category page
+ Product page