Don't try to store data files in the application folder - it is not a good idea and may be prevented by security policies anyway. Instead, store it in the location specified by
Environment.SpecialFolder[
^] - either CommonApplicationData or LocalApplicationData is fine.
Console.WriteLine("GetFolderPath: {0}", Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData));
You can then apply your application name or GUID and use that as a folder to store your data. It may change between machines, but it will be constant on a specific machine.