"What's the lowest you would take" is a lazy negotiating tactic. The goal is to get you to some theoretical bottom, and then try to negotiate from that point. It is the equivalent of the buyer trying to get the seller to counter-offer their own selling price. It is one thing if someone says that after a few rounds of negotiating, but it is something else when they come out of the gate with it.

In life, not just pinball, one way to lose my business if someone who is trying to sell me something starts the negotiations with, "Well what is it worth to ya?"

Yep, they are trying to get you to conter-offer your own selling price.