Is Ground wiring in a house expensive?
Well, I have brought a new house but there is some ground wiring which needs to be done in it.
SO, how much it costs?

Installing a ground wire can be expensive. This critical wire must be run from the electrical panel to each outlet. As you are already aware many of these outlets are not located in areas where the electrical contractor can simply drill into the floor below the outlet and push the wire up into the box. Sounds simple? It’s like fishing. You got to get the hook in just the right spot to catch the fish. Same with running a wire in a wall. Some times you can get lucky and get it right away, other times it can take quite a while before you can succeed.
You can bet the electrical contractor is going to charge for his or her time.

My suggestion is to ask the electrical contractor several questions on how they plan to do this. What is their experience doing this type of work? Some have special drills and lots of experience doing this type of work. Others will simply punch holes all over the walls in an attempt to get the wire to the outlet. Of course each one will charge different amounts for the project. But you need to add into the figure the damage they will be doing to the walls and ceilings to get this wire run.
My feelings are if you’re going to go through all this effort to run a ground wire, you should consider running a complete new wire instead. Sure it costs some more, but then you have the assurance that the older wire is not pinched or cut somewhere within the wall.

Also what is the need to run this gound wire?
Unless your planning to plug in with a grounded outlet such as a computer or high tech equipment. There is little use other then the protection of the outlet box itself. If that is indeed the case you would be better served using new wires as oftentimes the wire that does not have a ground is undersized for the loads you plan to put into it.

Well, that depends upon the area on which you need ground wiring.
By the way ya its a bit expensive than normal wiring.
So, don't worry just get it done.