asp/c# print only selected items using checkbox?

Question

I have a repeater shows items with checkbox for each item, i have a button that will print only the selected rows, but how to save the checked rows as a datatable or something like that:

 

this is the .aspx :

 

<tr>
                <td><asp:CheckBox ID="cbItem" runat="server"  ClientIDMode="AutoID" AutoPostBack="True" /></td>

                <td><asp:Label runat="server" Id="lblCampCode" Text='<%#Eval("ItemDesc") %>'></asp:Label></td>

                <td><asp:Label ID="lblBalUnits" runat="server" text='<%#Eval("InvoicBalanceUnits") %>'></asp:Label> </td>

                <td><asp:TextBox ID="txtExitUnits" runat="server"></asp:TextBox>
                    <asp:RegularExpressionValidator ID="revUnits" runat="server" Display="Dynamic" ControlToValidate="txtExitUnits" ValidationExpression="^\d+$" ErrorMessage="Please, insert a number." CssClass="text-danger"></asp:RegularExpressionValidator>
                    <asp:RequiredFieldValidator ID="rfvUnits" runat="server" Display="Dynamic" ControlToValidate="txtExitUnits" ErrorMessage="Insert number of units." CssClass="text-danger"></asp:RequiredFieldValidator>
                      </td>


            </tr>

 and this is the button event :

 

protected void btnExit_Click(object sender, EventArgs e)
{
    foreach (RepeaterItem item in rptItems.Items)
    {
        if (item.ItemType == ListItemType.Item || item.ItemType == ListItemType.AlternatingItem)
        {
            CheckBox checkBoxInRepeater = item.FindControl("cbItem") as CheckBox;

            if (checkBoxInRepeater.Checked)
            {
                Label lblCampCode = (Label)item.FindControl("lblCampCode");
                Label lblBalUnits = (Label)item.FindControl("lblBalUnits");
                TextBox txtExitUnits = (TextBox)item.FindControl("txtExitUnits");
                string CampCode = lblCampCode.Text;
                string BalUnits = lblBalUnits.Text;
                string ExitUni = txtExitUnits.Text;

            }
        }
    }

}

 i want to save the CampCode,BalUnits,ExitUni, for each row checked ?