I spent this week telling people to put it on their pricing page, next to the price. Three separate founders pushed back with the same worry: if they can negotiate, why would anyone pay list price?
They were right about the placement. The link works best where you're already losing the person: the end of a trial, the cancellation flow, a quote that went quiet, etc. On the pricing page it only makes sense when you were going to discount anyway, Black Friday style.
Every SaaS pricing page has two buttons: Buy now and Talk to sales. HAGGIN is the third: Make an offer. Buyers propose a price, seats and extras like a testimonial. You accept, counter or pass from an inbox. Your list price never moves.