Want to order by Meta Values (tweaking Post Order Widget)

I'm not much of a coder, but I can tweak PHP a bit. Basically I want to order by a custom meta value which integer called "price". The plugin orders by title, so thats what I'm changing to price, shown here. I saw some other posts about ordering by a meta value integer but the code logic was too different for my poor coder skills to reconcile with code in the plugin. Any help?

case 'title':
                $orderby = "price";
                $order = "ASC";

                break;

Here's the entire function:

    public function frontend_initialiser($vars){

    //Requête modifiable uniquement pour la toute première requête SQL.
    if(is_main_query() && $this->firstQuery){
        $this->firstQuery = FALSE;

        //On récupère la sélection de l'utilisateur
        $this->selection = isset($_GET['pow']) ? $_GET['pow'] : "";

        //Calcul du type (uniquement ceux gérés par l'extension) de taxonomie en cours.
        if(is_category()){
            $this->type = "category";
        }elseif(is_tag()){
            $this->type = "post_tag";
        }

        //Si le type est géré par l'extension, on récupère le slug courant.
        if($this->type != '')$this->slug = $vars->query_vars[$this->type . "_name"];

        //Le visiteur n'a pas demandé à changer le tri.
        if($this->selection == ''){

            //Par défaut, on garde le tri par défaut.
            $this->selection = self::POW_DEFAUT;

            //Maintenant, on va regarder si le tri par défaut ne serait pas différent de celui définit nativement
            if($this->slug != ''){
                //Recovering the conf different for different type of taxonomy
                $terms = $this->select_term($this->type);

                //If you look at the admin changed the default sort .
                if(array_key_exists($this->type, $terms) && array_key_exists($this->slug, $terms[$this->type]))$this->selection = $terms[$this->type][$this->slug];
            }

        }

        // We end up modifying the ORDER BY clause of the query.
        switch ($this->selection) {

            //Sélection par défaut : Tri du plus récent au plus ancien
            case 'dated':
                $orderby = "date";
                $order = "DESC";

                break;

            //Tri du plus ancien au plus récent
            case 'datea':
                $orderby = "date";
                $order = "ASC";

                break;

            //TRYING TO CHANGE CODE TO ORDER BY PRICE METAKEY VALUE
            case 'title':
                $orderby = "price";
                $order = "ASC";

                break;

            //for simple cases , the value of the item of the combo is what will be used in the " order by " of the SQL query .
            default:
                $orderby = $this->selection;
                $order = "DESC";

        }

        //On applique le filtre
        $vars->set('orderby', $orderby);
        $vars->set('order', $order);
    }

    return $vars;
}