The same domain name, on the same TLD, can cost noticeably different amounts depending on which registrar sells it to you, and the reason comes down to a few real factors.

Markup over wholesale cost. Every registrar pays the registry operating a given TLD a wholesale price per registration; what a registrar charges on top of that wholesale price is where most of the visible price difference comes from. Some registrars charge a significant markup, especially on a customer's first-year price as a promotional draw, then a higher renewal price in later years. Others, like NameBright, use an at-cost model instead, charging close to the wholesale price directly (see At-Cost Pricing, Explained).

Bundled extras. A higher price sometimes includes things bundled in, like privacy protection or promotional first-year discounts that don't reflect the ongoing renewal cost.

Introductory vs. renewal pricing. A very low first-year price is frequently a loss-leader, with the real, higher price only showing up at renewal.