I really agree with the cat adoption scheme, but I also think if you were to adopt from a dairy, they always have plenty of cats roaming around who are already trained to specifically kill rats.
I am having great results using Rat Zappers, available on Amazon (cheapest) or at your local Home Depot, OSH and Lowe's. No poison. Even better on mice and voles. Just be sure you find the right bait for your local residents.