The first 30 trial days are free. Before publishing the site you can choose between:
Hosting costs are $2.50 per month or $18.00 yearly. Free sub domain www.name-onescreener.com
PRO PLAN with existing Domain
Hosting costs for $4.50 per month or $42.00 yearly. No charges for the domain hosting.
PRO PLAN without existing Domain
Hosting costs for $4.50 per month or $42.00 yearly + registration domain www.name.com (Usually, they are between 10 and 20$ per year, but some top level domains cost up to 100$ and more (see https://dnsimple.com/tld-pricing).