Tightening the Belt in 2010

Here is an example of how calculating a per-use cost can help. Be warned, though, that cost per use doesn't work for everything. For example, you use life insurance only once, making its cost incalculable.

Clothing: Kathryn Finney, author of How to be a Budget Fashionista, recommends calculating a cost per wear of a garment before buying it. The more you wear it, the lower the cost.

She gives the example of a $500 winter coat that you wear 100 to 150 times a year over five years. That costs 67 cents to $1 each time you wear it. But if you buy a trendy top for $20 at Old Navy and wear it only three times, it costs $6.67 per wear. That makes a $20 top six times more expensive than a $500 coat.

Value, not low prices, should be your focus when shopping, she says.