Forget about the money, you aint gettin it if he doesnt have it. Thing to do is contact animal control and the police to document the attack and let them know that this dog owner is violating the leash laws with a potentially aggressive dog. Also alert the landlord so that if no action is taken and the dog does indeed attack another dog or a person, there will be evidence of negligence if nothing had been done.
Outside of that, get a Pit Bull or Rottie and let it exact some revenge.