Pathfinder offers a 7 day trial so that you can see if it is right for your store.
The trial starts when you activate your first campaign, and after the trial ends you will be billed for your first month.
Pricing is based on the amount of contacts that you have and can be seen here.
You must be connected to your ecommerce platform to start a trial.
You can turn on as many campaigns as you like, and there is no limit to the amount of emails that can go out.