The WooCommerce Request a Quote plugin for WordPress allows your visitors/customers to add products to a wishlist and submit an easy "request for a quote" from the Site Owner. This gives an opportunity for the Site Owner to give special rates based on the quantity/amount of the order. At the same time, allows the customer to bargain for better prices. It leads to better understanding and sales.
Demo: http://codecanyon.net/item/woocommerce-request-a-quote/6460218