Cost is based on what you will have done and if you will do it yourself (not recommended) or have a pro do it. Many years ago I paid $1500 to have a new 200A panel installed and feed my original panel as a sub-panel. Its worth every penny to know its done correctly and up to code since a mistake there could cost your home or a life. Let a pro see your current setup and give you a quote. I strongly recommend a licensed pro and a permit for the work.
As far as GFI in the panel, its up to you how you want things to work. Circuits for appliances like refrigerators should not have GFIs on them. Any circuit that will be in the bathroom or kitchen and will be for outlets should be GFI.
There is more to upgrading your outlets to grounded than simply adding the GFI. How is the wire being run now? Is it in conduit? Grounded outlets are great to have especially for computers and other equipment that requires a ground. I'll let the pro's take it from here.