Hi 9diov and welcome to the Tom's hardware forum.
I'd go with this:
Mobo: Gigabyte 890FXA-UD5
RAM: G.Skill 1600
same as Maziar recommends.
CPU: The Phenom II X6 1055T
is in ur budget or the Phenom II X6 1090T
is $60 more that ur budget.
Total with X6 1055T: $478.47 including shipping.
Total with X6 1090T: $558.47 including shipping.