The battery terminal itself is pretty cheap as in $10.00 to $20.00 for two battery terminals if you buy them at an auto parts store.
But if you take the vehicle to a shop to have them replace the battery terminals they'll markup the price of the battery terminals they sell to you to make a profit which is part of business.
The labor itself to replace the battery cables should cost from $30.00 to maybe $50.00 or in some places $100.00 depending on the shop.
If you have someone that can do the job for you then it will be much cheaper than a shop.
You only need to cut the old battery cable terminal off or unbolt it and replace it with a new one which is very easy to do.