I will start asking questions to get him or her to question their decision.
I may throw out examples such as isn’t it better to spend more than you thought then less than you should.
That's a question asking for agreement, i.e., consent. If you don't get consent, you're not moving forward.
I will then tell a story of a customer that did the very same thing only to discover within a few days weeks months the need to replace the product.
I have been known to ask customers what kind of suits they purchase then ask why. I know the customer at this time and I pretty much know what to expect if they purchase suits from penny’s or warehouse or custom. When I am informed of the higher price suits due to maintaining color over years and use I now can take the faucet at a cost to them instead of price. Cost is based over the life of the product where price is a onetime issue.
That's a viewpoint via analogy asking agreement, i.e., consent. If you don't get consent, you're not moving forward.
If "I cannot afford the item" enters the equation which we know to be a stall is thrown into I must be able to explain why they cannot afford not to move in the right direction today. Sometimes I must be able to beat back the reasons a customer will not choose the best price.
Again, needs consent by the prospect to your point of view. If you don't get consent, you're not moving forward.