Did you pay to get an account with them? I have a business account with amsoil and get everything at reduced cost. It is $6.40 a quart for the 4 stroke 10W-30 with my account.
2013 Gravely 460Z 29EFI
2011 Gravely 36GR
2008 Gravely 160Z
2004 Gravely 34Z
1998 Lazer Z HP 48 (old faithful)