Existing registrants for the David Thaddeus seminar can make payment via PayPal here. A PayPal account is not necessary to complete payment. Structural Systems 2012 - AIA Northern Virginia Members Members may pay the $320 fee below. Structural Systems 2012 - Other AIA Chapters Members may pay the $350 fee below. Structural Systems 2012 - Non-Members Non-members may pay the $390 fee below.