Everyone knows weddings are expensive, and it turns out those costs aren't driven purely by consumer demand.

An April 2016 investigation from the nonprofit group Consumer Reports found that vendors charge a "wedding markup" to artificially inflate the cost of nuptial celebrations.

Consumer Reports tasked secret shoppers with reaching out to various wedding vendors — photographers, florists, and caterers, to name a few — in five metro areas for quotes on wedding services and anniversary party services "that were identical in every other respect."

Nearly 30 percent of the time, vendors provided the secret shoppers higher quotes for wedding services than anniversary party services.

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A July 2015 video by Vox addressed the wedding markup as well.

In the video, a man calls a vendor asking for a quote for a family gathering event of around 125 people on April 16. Another woman in the video calls a vendor for a wedding quote with roughly the same guest count on April 16, and she receives a quote for $17,000, which is $2,000 higher than the quote the man received for his comparable event on the same day.

Videographer Johnny Harris explains in the video why weddings cost so much more than comparable events:

"There's this economic concept called asymmetric information. With most things you buy, you have a pretty good gauge on what you're getting for what you pay for. You're pretty sure that an $8 avocado is way too much because you're bought avocados before. Familiarity with a market produces balanced information between buyers and sellers so they can settle on a fair price."

Because most people are unfamiliar with wedding costs, this makes it easier for vendors to charge higher prices:

"Most people shopping for wedding stuff have very little, if any, experience with what they're buying," Harris says. "Cake, dress, napkins, catering, venues, flowers, this is stuff that you just don't buy very often, so you don't have a very good gauge on what you should be paying."

How to put your foot down and negotiate better prices.

Harris says in his video that it's important to demand a price before hearing a sales pitch from vendors:

"We vendors might hate it, but it's the fair thing to do."

The Consumer Reports article offers similar advice. It states that even though its sample size was only 40 vendors in 12 states, it is still proof that consumers should educate themselves on wedding pricing and negotiation to save money on wedding planning costs:

"While those data points aren’t enough to indict an entire industry, they’re a warning to wedding shoppers to read fine print, ask smart questions, and negotiate before signing anything. In fact, in a few cases we found that it wasn’t hard to strike good deals with those same vendors."

Having a smart negotiating strategy while planning your wedding could mean the difference between organizing an affordable celebration, or becoming one of the many couples who break the bank on their big day.

[H/T Business Insider]