Add the items in the datagrid in text change event asp.net

HTML:

<form id="form1" runat="server">
    <div>
        <asp:GridView ID="gvProduct" runat="server" AutoGenerateColumns="false">
            <Columns>
                <asp:BoundField DataField="ProductName" HeaderText="ProductName" />
                <asp:TemplateField HeaderText="Prices">
                    <ItemTemplate>
                        <asp:TextBox ID="txtPrice" AutoPostBack="true" OnTextChanged="Price_TextChanged"
                            Text='<%# Eval("Price") %>' runat="server"></asp:TextBox>
                    </ItemTemplate>
                </asp:TemplateField>
            </Columns>
        </asp:GridView>
        <br />
        Total Price:
        <asp:Label ID="lblTotalPrice" runat="server"></asp:Label>
    </div>
    </form>

C#:

protected void Page_Load(object sender, EventArgs e)
    {
        if (!this.IsPostBack)
        {
            DataTable dt = new DataTable();
            dt.Columns.AddRange(new DataColumn[2] { new DataColumn("ProductName", typeof(string )),
                                                    new DataColumn("Price", typeof(int)) });
            dt.Rows.Add("Stumps", 400);
            dt.Rows.Add("Bat", 500);
            dt.Rows.Add("Ball", 50);
            this.gvProduct.DataSource = dt;
            this.gvProduct.DataBind();
        }
    }

    protected void Price_TextChanged(object sender, EventArgs e)
    {
        GridViewRow row2 = (sender as TextBox).NamingContainer as GridViewRow;
        int price = 0;
        foreach (GridViewRow row in gvProduct.Rows)
        {
            price += Convert.ToInt32(((TextBox)(row.Cells[1].FindControl("txtPrice"))).Text);
        }
        row2.Cells[1].FindControl("txtPrice").Focus();
        this.lblTotalPrice.Text = price.ToString();
        
    }