JC WooCommerce Set Your Price plugin allows users to pay what they want for your product as long as that price is above the specified minimum price. Evaluate product prices by setting how much you think a product is worth and let customers decide how much they are willing to pay, generate reports based on how much customers are Paying per product.

Demo: http://codecanyon.net/item/jc-woocommerce-set-your-price/10028616