I'm using:
https://market.x-cart.com/addons/call-for-price.html
... it works fine, but I'm tweaking it to my liking, with an image instead of the text "Call for Price"
Here's a page that is using it:
https://blainespartynetwork.net/partypoints/giftmall/blaines-designs/sleep-like-royalty-on-this-beautiful-...oom-suite.html
The Price and "Add To Cart" button was replaced with the image: Blaine's Party Network Honor System - This Item Features Off-Line Negotiation & Payment.