When choosing a platform many people only look at build cost. Ongoing costs matter too: hosting, domain, SSL (often bundled), and time or money for updates and support.
WordPress — hosting is often cheaper for small sites; you need to update core, theme and plugins. Some plugins are paid (annual licence). With WooCommerce, payment, invoicing or integration plugins may each add cost.
PrestaShop — hosting may need to be stronger for large catalogues. Paid or free modules and shop updates are part of maintenance. A single e-commerce platform can be cheaper at scale than many paid WordPress extensions for a very heavy shop.
In short: small site + blog or small shop — WordPress often costs less to run. Large catalogue, complex rules, warehouse integrations — PrestaShop can be more predictable long term. Ask for an estimate that includes annual costs, not only the initial build.