"On occasion, vendors will donate or discount based on the exposure they will receive having their work be on display in front of high-profile guest or after event details where the vendors' names will be shared with media outlets," says Cyndi Rosenberg, the director of Catering Trump International Hotel & Tower Chicago.

Kate's dress -- a state secret

However, for many vendors, events like the royal wedding can be a bust. Everyone down to chefs and busboys has to sign a confidentiality agreement, making it impossible for them to use their labors to gain a marketing edge, Richardson-Hall says.

Many designers don't realize the pitfalls of creating gowns for big events, says George Simonton, a veteran fashion designer. Sometimes designers don't even get paid, he says, though he adds that the late actress Elizabeth Taylor was one client who was very good about her bills. She paid top dollar for the best designer clothes.

A designer wedding gown, like the one being created for Middleton, probably costs about $10,000 to create, Simonton says. Most American brides typically spend around $1,000 on their gowns.

While the name of Middleton's dress designer is virtually a state secret, that's not the case with some other parts of the wedding. For the cake, Leicestershire-based cake designer Fiona Cairns was picked to create the mother of all desserts. McVitie's Cake Company will create a chocolate biscuit cake, made from a royal family recipe, for the reception.

For the bakers, like all the other vendors, the pressure is enormous. "You really can't mess up the royal wedding cake," says celebrity baker Duff Goldman, whose cakes have been used at Super Bowl events and other high-profile affairs. "You just want to make sure that everything is absolutely perfect."

Goldman, who would have designed a 15-tier tribute to the happy couple had he been asked, said cakes of this nature can cost as much as $50 a slice. Six-figure cake costs are not unheard of.

The reception will be held at Buckingham Palace, so there will be no cost for renting a hall, which typically runs couples more than $12,000, according to TheKnot.com. The palace, of course, has its own chef, kitchen and event staff, which will be fully engaged for the event.

"The wedding is going to be a very special event for the whole team within the palace," royal chef Mark Flanagan said in a YouTube video released by the royal family. "It's a chance of a lifetime to be part of a wedding for a future king and will be one of the most high-profile events we could ever wish to be involved with in our lives."

When dealing with high-priced weddings and other affairs, caterers have to master the art of giving the people what they want. Waldorf Astoria Executive Director of Catering Jim Blauvelt says his clients occasionally grow tired of fancy fare, because they eat it so often, and like nothing better than a meal of short ribs and mashed potatoes. At Buckingham Palace, the event staff will choose from a selection of 150 passed hot and cold hors d'oeuvres for the wedding reception.

Planners of the royal wedding must plan for every imaginable contingency, from dietary issues to guests forgetting their invitations (which planners say does happen). Robert Schwab, the director of catering at the Beverly Hilton, said through a spokesman that last-minute changes, even during the event, are common. Once, his staff had to change the seating arrangements before a televised show since an A-list celebrity couple could no longer sit next to one another because they had broken up that day.

The UK foots some of the bill

British Prime Minister David Cameron, who announced sweeping budget cuts in October, has declared the wedding to be a national holiday. Taxpayers, of course, pay to keep the family in the style to which they have grown accustomed -- to the tune of 41 million pounds (or almost $68 million) a year. According to the British press, funding for the royal household has been frozen at about 7.9 million pounds for more than two decades. The queen is reportedly seeking a raise to cover her increasing expenses.

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The government will probably pick up much of the cost of the procession through London from Buckingham Palace to Westminster Abbey. Officials are expecting 600,000 visitors to wish the young couple well on their special day, far surpassing the 159,000 people who came to the Dallas area for the last Super Bowl.

While William and Kate will avoid some of the fees that ordinary Americans pay -- by virtue of being A-list celebrities and having a palace and a full staff at their beck and call -- there are many extra costs associated with this wedding that the average couple doesn't have.

For example, a final cost to consider -- the cost of cleaning up the streets of Central London -- may top 40,000 pounds.

Ultimately, paying for the wedding is probably the least of the concerns for William and Kate. But if they can survive the party and the publicity, they will be one step closer to figuring out how to handle married life under the white-hot glare of the media spotlight.

2010 Real Weddings Study Results
Category2010 National Average Spend
Overall Wedding (excluding honeymoon)$26,984
Ceremony Site$1,393
Reception Venue$12,124
Reception Band$3,081
Reception DJ$900
Wedding Gown$1,099
Wedding Cake$540
Ceremony Musicians$503
Catering (cost per head)$61
Wedding Day Transportation$667
Rehearsal Dinner$1,127
Engagement Ring$5,392

Data: TheKnot.com & WeddingChannel.com