I'm sure by now you've already met with your florist but since I'm new and just seeing this, I suppose I'll comment!

I am a florist in Kansas so flower cost will differ some depending on locations. White callas are generally the least expensive when compared to colored varieties. It is pretty typical for them to run about $6 a stem on average. The great thing about callas is that you really can get by with using less of them because they do make such a huge statement! Roses on the other hand, generally run about $3 a stem for all colors.