Existing Unity3D game development and porting to Android/iOS

I require a number of "feature/graphic enhancements" for an exitsing Unity3D game together with a port to both iOS and Android. Eventually this will also become a facebook project so knowledge of facebook development an advantage but not a requirement at this stage. Please provide examples of your Unity work together with a ball park monthly rate with your proposal. I envisage up to 20 weeks work if all the skills required can come from a single source. Documentation and existing Unity3D project will be supplied when the relevant partner has been selected.