WooCommerce Pay Your Price is a WooCommerce Extension Plugin using which users can pay their own price for the products there by giving your users more importance which is likely to get you More Sales. Pay Your Price can be used to Accept Donations, understand what Prices your Products command in the Market etc. You can force users to pay within a range by setting a Minimum and Maximum Price.
Demo: http://codecanyon.net/item/woocommerce-pay-your-price/7000238