Grappling dummies are freakin' expensive. You're probably looking at an easy $400 investment before shipping like the I&I Sports Grappling Man Dummy
aka the "Bubba Dummy" (pictured below).
I know that Mark Hatmaker released a DVD called the Floor Bag Workout
which outlined a lot of suplexes and slams utilizing a 100lb heavy bag if you don't have a dummy available. It's kind of hard to find, but it's definitely a reasonable alternative.
It doesn't matter if you agree or disagree
... As long as I don't bore you and I spark a moment of thought, my goal is achieved
Queng leon queng tigre ecu tacacut, queca pa? - Pampangan Mandarigma Motto