use string helper with currency

[eluser]Michael Nielsen[/eluser]
Ok but now I've submitted my form but I can't get it working just right.

Code:

function add()
    {
        $this->load->helper('form');
        $this->load->library('form_validation');
        $data['randomValue'] = random_string('alnum', 9);

        $this->form_validation->set_rules('productName', 'Product Name', 'required');
        $this->form_validation->set_rules('productPrice', 'Price', 'required');

        if ($this->form_validation->run() == FALSE)
        {
            $this->load->view('product_add', $data);
        }
        else
        {
            $price = '$'.$_POST['productPrice'];
            $this->db->insert('product', $_POST);
            echo 'Complete';
            echo $price;
        }
    }

If you look at the last line of the function I echo the price which comes out with the $ sign however it's been accepted into the db because it wasn't in the original $_POST.

Any solutions?