Is it possible to manipulate, in real time, `get_price_html()`?

I am currently working on an eCommerce website, where I need the Product Price to Output the sum of the following equation:

Product Price + (Character Count * ￡2)

The Product Price is entered via the Product Page’s Back end.

Character Count
The Character Count counts how many letters a shopper enters into the Input Text Box. To achieve this Character Count, I entered the following jQuery code into the Single Product Template:

<script type="text/javascript">	
jQuery(document).on('keyup', '.product-custom-text', updateCount);
jQuery(document).on('keydown', '.product-custom-text', updateCount);

function updateCount() {
    var cs = jQuery(this).val().length;
    jQuery('#character_count').text(cs);
}
</script>

Then, to Output the Character Count, I entered the following code into the functions.php file:

<?php
function letter_counter(){
    echo '<span id="character_count"></span>';
}
add_action('woocommerce_single_product_summary', 'letter_counter', 29);
?>

Where I am now stuck is on putting together my Character Count and ￡2 and then ‘linking’ this to the get_price_html() function so that said function Outputs the above sum.

Any suggestions, or directives, on how to achieve this would be greatly appreciated.