Beyonce and Jay Z are reportedly in final negotiations with E! - who produce 'Keeping Up with the Kardashians' and are believed to be part-funding the nuptials - about giving a 'short set' at the celebrations.

A source said: "Jay Z and Beyonce will also perform at the wedding, as long as their last-minute negotiations with E! work out. The two have demanded $2 million for a short show". Kim is said to have splashed out another $2 million on one wedding gown - and she hasn't decided yet whether to wear it.

The brunette beauty reportedly asked Alexander McQueen's Sarah Burton - who designed the gown the then-Kate Middleton wore to marry Britain's Prince William in 2010 - to create one of three outfits she is considering wearing on the big day.

A source said: "She has called on Sarah Burton to design one of her options. Kim wants the low-cut v-neck look that Kate had, but much lower, and she wants her gown to be tight fitting to show off her svelte figure. Her gown is estimated to cost $2 million. And no one will see the gown until she walks down the aisle."

"There are three gowns that were made just for her and she hasn't even decided yet between them." While E! are footing part of the bill, the couple - who have 11-month-old daughter North together - are also splashing out another $7 million for expenses including catering.

A source told RadarOnline.com: "The two have planned a rehearsal dinner that costs an estimated $650,000". And they are paying for a lot of that. Chefs from around the world are being flown in to prepare dinner for the rehearsal night and the reception dinner after the wedding. High-end and extensive security is costing $3 million, flowers are $1 million and food is about $2,000 a plate."

As well as Beyonce and Jay Z - who were initially reported to be snubbing the ceremony because they didn't want to be filmed - Lana Del Rey is also believed to be performing for the guests as they quaff $6,000-per-bottle champagne. The celebrations will end with a $200,000 fireworks display.