Hi,
You can do this by using Asp.Net and you probably do not need any client script do get the
Sum of GridView Column values in the Footer. Its written both in C# and Vb.Net. It also handles "paging" issues, such as how to get the sum in each page of the GridView along with the Grand total, shown in every page (if GridView paging in enabled).
Happy coding.
Arun