Who the economic buyer is
The economic buyer can say yes when everyone else says no, and can veto a deal everyone else supports. They control the budget the purchase comes from, or have the authority to find money that isn't budgeted. In a small company it may be the founder; in a larger one it may be a department head, a finance leader or an executive, depending on the size of the deal. The economic buyer is often not the person you speak to first, and not necessarily the person who will use the product.
Example
A head of sales loves the product and wants to buy. When the rep asks how similar purchases were approved, she explains that anything over a set amount goes to the CFO. The rep asks for a 20-minute call with the CFO to cover the cost case, and the champion agrees to set it up.
Why it matters
Deals stall when the seller has never spoken to the person who approves the money. A champion can be enthusiastic and still lack the authority to sign, and late surprises such as a budget freeze or a change of priority usually come from the economic buyer. Knowing who they are, what they care about and how they judge purchases like this lets you shape the deal around their criteria instead of finding out at the end.
How to practice it
Practice the questions that identify the economic buyer without sounding pushy, such as 'Who else will weigh in on a decision like this?' and 'When you've bought something similar, who signed it off?' Then practice asking your champion for access to that person, with a good reason the meeting helps them too. The stalled-deal roleplay, where the champion has to 'run it by my boss', is a good drill for this.