Talon is a better bait to use than ratsack as it's a back to base poison that will have the rat feel sick and then head back to the nest and eventually die. Then the other rats will attempt to eat him and then the same eventual outcome happens to them, by this cycle they will all be eventually be eradicated within the nest and not inside your home or shed etc.
and yes it is a tad more expensive but a far better outcome in my opinion.
Cheers,
BB.