Make an offer by Abakira

Buyers propose a price on your product page. You accept, decline or counter, or let your rules answer for you, and the buyer pays the agreed price in Shopify’s own checkout.

A theme app block, no injected script. You place it in the theme editor; nothing is written into your theme’s code, and the form still works if JavaScript is blocked.
The agreed price, with shipping and taxes. An accepted offer becomes a Shopify draft order: the buyer pays exactly that price, and the checkout adds shipping and taxes. No product, variant or discount code is created.
Low offers never reach you. Below your floor, the buyer gets a polite decline and you are not disturbed.

Install it from the Shopify App Store, then open it from Apps in your Shopify admin.