Galhano //127.0.0.1

String.Format("{0:f2}",value);
String.Format("{0: #,#.00",value);

In GridView:

<%# String.Format("{0:f2}",DataBinder.Eval(Container.DataItem, "pricerange").ToString())%>

<EditItemTemplate>
<asp:TextBox ID="txtPrice" runat="server" Text='<%# String.Format("{0:#,###}",Bind("Price")) %>' />
</EditItemTemplate>

<EditItemTemplate>
<%# String.Format("{0:C}", Convert.ToString(Eval("Amount")) ) %>
<EditItemTemplate>

More info:
http://msdn.microsoft.com/en-us/library/system.string.format.aspx
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.boundfield.dataformatstring.aspx