A domain is a recurring cost, not a one-time purchase. Registrars routinely advertise a low introductory registration price and then renew at several times that amount. A $1 first year followed by $20 renewals costs more after three years than an honest $12 flat price — and transferring away later adds friction and fees.
DomRenew puts the renewal price next to the registration and transfer price on every page, ranks TLDs by long-term holding cost, and flags extensions where the renewal markup is steep.