Any ideas or suggestions with some flowers that will compliment calla lilies? We're trying to keep all the flowers white without any roses. I don't know anything about flowers so this has been very challenging. Any input would be appreciated

Oh, the wedding colors are black, silver and white.
Re: Suggestions for white only flowers?
You don't say if you are doing your flowers yourself, using a florist, or getting them online. This would affect your price.
If you go to the following link, it is a website that shows you all the flowers they have in white.
http://www.fiftyflowers.com/flowers/WeddingFlowersPureWhiteFlowers_8.htm
Peruse it for ideas. If you are using a florist, they are getting their flowers from similar bulk flower sites, and will increase the cost by 50% or more.
I have a while until my wedding (August 2011), so I'm not really finalizing anything yet. However, I'm leaning toward white calla lillies, oriental white lillies (because I love the smell, and there are usually 3-5 blooms per stem), white roses, and baby's breath.
I see from your bio that you are getting married in the summer. Many of the flowers on that website are available then, and the costs might be cheaper. Also, ask around your family & friends. They may have gardens, or know someone who does, that will have flowers available to help keep the cost down.
Good luck.
With All the Trimmings