Custom Javascript/HTML Form

I am designing a checkout cart for a translation company. I need a simple HTML form consisting of a textarea field and a submit button. The page that the form is in should have text reading "Words: 0" and "Price: $25". As the user types in the text area, the text reading "Words: 0" and "Price: $25" should update automatically to show the correct number of words and correct price. The minimum price is $25, but once a 26th word is entered, the prices should increase along with each additional word. In addition, if a user types in a word longer than 25 characters, a javascript pop-up should alert them that words over 25 characters aren't allowed and should cut off the word at the 25 character mark. Pasting text into the text area should perform the same word count and price calculation functions. Once the user hits the "submit" button, the textarea, word count, and price should be passed as form variables. The form has to be very stable and work exactly as described.