Would you pay $45 for a carry-on bag?

Spirit Airlines has become the first U.S. airline -- and maybe the first airline in the world, according to The Wall Street Journal’s Middle Seat Terminal blog -- to charge passengers for carry-on bags.

Charges will range up to $45 each way, with a low of $20 for members of the $9 Fare Club who reserve a bag in advance (and don’t forget your $39.95 annual club membership). Non-members can carry on a bag for $30 if they pay in advance.

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Lest you think you can disguise your carry-on bag as a purse or computer case, be warned that Spirit will have “bag sizers” at the gate to make sure your “personal items” don’t measure more than 16 by 14 by 12 inches.

Those who pay for carry-on bags will board first, Scott McCartney of the Middle Seat Terminal reports, making it easy for the airline to make sure no one else is trying to sneak a bag aboard without paying.

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"In addition to lowering fares even further, this will reduce the number of carry-on bags, which will improve in-flight safety and efficiency by speeding up the boarding and deplaning process, all of which ultimately improve the overall customer experience," Spirit's chief operating officer, Ken McKenzie, said in a news release. "Bring less; pay less. It's simple."

Spirit touts its fee structure as a way for the airline to offer lower fares while giving "customers the option of paying only for the services they want and use rather than subsidizing the choices of others."

Spirit already charges a host of other fees: $5 each way to book a flight on the phone or in person, $8 to $20 for preferred seat selection, and $2 to $3 for a soda, plus, of course, $15 to $45 to check bags. SmarterTravel has a chart listing fees for all major U.S. airlines.

At least Spirit isn’t charging extra to use the restroom -- yet.

But why not, suggests our friend Stacy Johson at Money Talks News?  "It’s completely unfair for me to subsidize tiny bladders," he writes. He suggests a host of other fees by which airlines can make more money, including charging passengers by the pound, charging children more and charging people extra if they wear clothes. We hope he is joking.

Spirit's new fee schedule goes into effect Aug. 1.

Spirit is currently offering flights for 1 cent each way to its $9 Fare Club members (it sometimes offers $9 fares). However, that price doesn’t include fuel costs or taxes. The 1-cent fare from Detroit to Las Vegas, for example, actually is $72.93 each way -- not including bags, drinks or seat selection. Add $20 for a carry-on bag, and your 1-cent flight actually costs $92.93. And that’s if you bring your own drink.

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The U.S. Department of Transportation fined Spirit up to $375,000 last year for violating consumer protection rules.

The real problem with the a-la-carte airline fees is that it’s difficult to compare prices when you’re looking for flights.

As “jrh0” wrote in a comment to the WSJ Middle Seat Terminal blog:

I'd like to see WSJ do a series on “Truth in Pricing.” It could compare advertised prices like “Penny Fare” with realistic actual costs from different vendors within various industries. Suggested industries, for starters, would be cell phones, rental cars, movers, home builders, banks, and concert venues. I don’t mind paying a fair price, I just want to know up front and be able to compare prices. While Spirit’s fees may not technically be hidden, it takes time to research fees for various vendors, and one is likely to encounter some surprises in the end. Nothing sours me on a business more than surprise fees.

We agree. And we have to wonder: Are the other airlines going to follow suit and charge for carry-on bags?

Related reading:

• Avoid these 7 nasty airlines fees
• Flier’s guide to new airport hassles
• 3 tips on scoring a low airfare