Hey Joe, that's called the "stone soup" approach.

Another approach that may work:

Positive approach: "Well dear, we spent all those thousands to attain our goal, and we're almost finished. Another thousand or 2, and we're there!"

Negative approach: "Well dear, we're almost finished. Only 1 or 2 little minor things left to buy! It would be a shame to waste all those thousands by capping our spending now."

This is all good fun, but everyone knows that Donna-Ski would see these amateur ploys coming a mile away. I think Brettski would only get "the look" for his scheming. \:D