On another online community I frequent, one person came up with the concept of shoe math. It goes like this.

"I saw this awesome pair of shoes for $358. They were so cute, I bought them but then I changed my mind and returned them." OR "I managed not to buy them." Along those lines. This translates into:

"I didn't spend the $358. That means I'm now in the black for $358, which I'm now entitled to spend."

And it can be applied toward anything. Use Shoe Math for vacation spending, restaurants, any time where you want to justify spending money that you avoided spending on something else.

Viva Shoe Math!

(Disclaimer: I'm not advocating this)