I have planned and implemented a SharePoint Portal and Collaboration solution for my organization. While you most likely won't get any cost estimates due to the number of factors involved, here are some general thoughts.
- With a fairly out-of-the-box implementation, you should plan with 6 months. It is obvious that any outside expert help you can get will speed up any part of your project.
- You should always plan for additional costs like third-party web parts or tools that compensate for certain shortcomings of the platform.
- We are moving what we can to the cloud, but SharePoint is not inexpensive if you need your own instance that you can customize. Attractive SaaS pricing only applies to shared instances where you're locked in to a narrow set of standard features.
- Last, but certainly not least. You need to answer the question of purpose and intended usage scenarios first. SharePoint is above all a platform. You can do pretty much anything. Someone who knows it well will be able to tell you how much effort it takes to get to where you want to go.
Feel free to take a more detailed discussion offline.