With Magento 2 Price Match extension - Magento 2 Found a lower price Tell us Extension, You can Place 'Found a lower price Tell us' button on the product page and let your customers inform you about lower prices on the same items in other web-stores.
https://www.magearray.com/found-a-lower-price-tell-us-price-bargain-extension-for-magento-2.html
https://www.magearray.com/found-a-lower-price-tell-us-price-bargain-extension-for-magento-2.html