18. Justin Timberlake and Jessica Biel - 2012
Estimated Cost: $6.5 million
These two spared no expense when they tied the knot in Puglia, Italy. They rented the entire Borgo Egnazia luxury hotel for the festivities in 2012, where Jessica wore a custom Giambattista Valli Haute Couture gown (her veil was encrusted with her heirloom pearls). Of course, Justin serenaded his bride with a song he wrote for her as she walked down the aisle.