Build intranet using Google Apps

We have a Premium account with Google Apps and our company team is already having accounts there. We want you to use Google sites (freely available with Google Apps) to build an intranet like website. The webiste will need to have a customized look. Login facilities (available with Apps), calendar (available with Apps), announcement section (available with Apps) and a download section. What we may need is adding some small modules like Admin being able to upload documents for download or adding a forum etc. Only coders who have worked with Google Apps need apply. Pls give me a time and cost quote. Also, do you see any limitations on the functionality that we need? Please quote with a cost breakup (design cost, cost for customizing google apps) I will only consider bids that have this breakup, as I do not have the time to go back and forth for this information. Thanks in advance.