Another option is to go completely fake. I'm currently working with a bride who is on a tight budget. She would LOVE to have the towering decorative fondant cake, but it's just not an option. We have opted to create a tall, luxurious, fake wedding cake! The bottom layer will be real so that she will be able to cut the cake with her husband and as for the guests, we will have multiple sheet cakes that the kitchen staff will cut and serve to guests.
There are many sites that sell or rent fake wedding cakes, or kits that you can make them yourself. If you decide to contract a bakery to make your fake wedding cake, you will more than likely have to purchase your sheet cakes from them in return. Be sure to check with them before signing a contract.