The Wall Street Journal says that weddings are much more expensive than people think, stating the following:

Your $18,000 wedding? It may really end up costing you between $90,000 and $200,000.

That's because the biggest cost of every dollar you spend is invisible. It's all the money you'd accumulate if you saved it instead. Over long periods, this cost dwarfs the mere sticker price, often by a factor of several times.