I wanted to break my children of a bad habit they had of dropping things into my shopping cart without first checking the price. So now there’s a money rule they must follow when we go shopping: If they put something in the cart and they can’t tell me how much it cost, out it goes.

There are two reasons for the rule. First, since they aren’t paying, they often don’t think they need to know how much something costs. But even when I’m not paying for something, I try to be mindful of its price. I want to be a good steward over my money and the money others are spending on me.

Second, I want my children to learn that they should always — always — ask how much something costs lest they find out later that it was beyond their means.

So I read with interest the story about Bonnie Lieb, a Virginia woman who was shocked — shocked — to learn too late that her 30-minute Uber ride to Reagan National Airport from her home during the recent blizzard cost $640.94.

“I nearly passed out,” Lieb told The Washington Post’s Katherine Shaver.

But it was clear to me what went wrong. Here are the money mistakes she made and what you can learn from her experience:

Mistake No. 1: Lieb said she had heard from neighbors that the ride to the airport could cost between $50 and $70. Never rely on what people think something costs. Confirm for yourself. It took me less than 30 seconds online to get an estimate from Uber on how much a ride from my home to Reagan National Airport would cost. In Lieb’s case, it turns out the base price for the SUV service she ordered was $144.76, Shaver reported. Apparently she hadn’t noticed the cost of the base fare.

Mistake No. 2: She didn’t take the time to do the math before agreeing to take a ride. Because there was a blizzard, Uber imposed a surge price of 4.4 times the base price to transport Lieb to the airport. The surcharge added $492.18 to her bill.

Mistake No. 3: She blamed the business. “How they justify $640 is beyond me,” Lieb said. Look, it’s basic economics. Businesses will charge what they think they can collect. The surge pricing works for Uber because some folks will pay a premium to get a ride during certain times like a blizzard. It’s not Uber’s fault that Lieb didn’t do her homework.

In the end Lieb got some grace. Uber offered her a credit of $160, or 25 percent of the fare she paid, according to Shaver. Learn from Lieb’s mistakes. And maybe in the future she’ll use my price rule.

Color of Money Question of the Week

What’s the most expensive thing you bought without realizing how much it would cost? Send your comments to colorofmoney@washpost.com. Please put “Uber Lesson” in the subject line. I’d also love it if you tell me who you are and where you live. Names keep the Internet trolls and the discourteous away.

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Color of Money Columns

Here are my columns for the past week:

Small-business workers may get retirement savings help

If you work for a small business and are worried about your retirement savings, read Post reporter Jonnelle Marte’s story about the Obama administration’s plan to make it easier to save for retirement.

A proposal in President Obama’s budget “would make savings account plans more available to workers by lowering the costs for small businesses,” Marte wrote this week. One way to make it easier would be to allow groups of small businesses to share the cost of offering a retirement plan to workers.

As Marte writes:

Such joint efforts, known as multi-employer pension plans, are already possible but for companies in similar industries. The latest proposal would remove the requirement on industries, making it possible for small businesses in different fields to work together to offer retirement plans to employees. As a plus for savers, those workers who change jobs to work with another company participating in the group plan would be able to keep the same account.

Here are some other parts of the plan, Marte reported.

— Employers with more than 10 employees could automatically enroll workers into an IRA if the company doesn’t offer a retirement plan.

— Employers would have to offer retirement plans to part-time workers who have worked for the company more than 500 hours a year for at least three years.

If approved by Congress these measures could help people save more for retirement.

Blizzard = Budget Time

For last week’s Color of Money Question of the Week, I asked you to tell me about how you budget.

“I have not done a budget because it seems like no two months of the year are ever the same for me,” wrote TL Touzin of Colorado Springs, Colo. “I’m an active-duty military officer, and in the last three years I have moved from Washington, D.C,. to Colorado, sold a condo, bought a rental property, deployed twice (spending a total of 13 of the last 36 months serving overseas), moved five times (including the deployments), and there have been weeks and even months at a time when I’m on the road, in ‘Temporary Duty’ (TDY) status. With such wild fluctuations, I can never do a reasonable spending trend analysis to set a budget. I’ve still managed to save very well, but it’s frustrating to lack decent baseline understanding of my financial habits.”

Wow, that’s a lot of moving around. But I’m proud of Touzin’s service to our country and to her finances.

Gawain Douglas of Tucson, Ariz., said she and her husband are finding it hard to make the time to budget. She wrote: “We have three children, and between all of their homework, activities and our work and meetings, we just can’t seem to prioritize setting time aside for managing a budget. Often, the only time we have to think about, or talk about money, is late at night — and that is not a good idea. Not having a budget frustrates me and stresses me out. It is sort of like exercising, I know I should do it more, but have a hard time sticking with it. Would love to hear if you come up with a good plan for people like me.”

For Douglas and those like her I suggest you meet with a budget expert at a nonprofit credit-counseling agency. Here’s the link to find one in your local area.

Betty Sandbeck, formerly of Alexandria, now in Naples, Fla., wrote: “I’m 65, retired since 2007. I have never had a formal budget. I saved 20% of my gross income, starting at age 22. I invested in the stock market and put money in an IRA. When 401ks came out, I went for the max. I worked 12-hour days. The money built on itself. I’m lucky now to not have to worry about money, but I’ve always lived below my means.”

Sharon Williamson of Tacoma, Wash., said she’s never had a traditional budget, but she and her husband have found a way to stay on track. She wrote: “I’ve always aggressively tracked my spending by category, and reviewed it monthly, then made adjustments. The first time I started tracking this way (in 1995), I saw I had spent $200 eating out, but had not fully paid off my credit card that month (I owed about $500). Just having that holy cow moment stopped the extra spending in the luxury categories and got me on track. I paid off the card the following month and have never had consumer debt since. I still track this way and have over 20 years of data to review for inspiration. This helps to prevent spending creep as our income increased.”

I love this testimony. A “holy cow” moment can help you manage your money for the long term.

Readers may write to Michelle Singletary at The Washington Post, 1301 K St. NW, Washington, D.C., 20071, or michelle.singletary@washpost.com. Personal responses may not be possible, and comments or questions may be used in a future column, with the writer’s name, unless otherwise requested. To read previous Color of Money columns, go to washingtonpost.com/business.