I'm not selling the theme, I'm selling the integration service, For this every buyer needs to send the License PDF to prove that have the rights to use this theme in their site. If the buyer proves that have the rights, I don't suspend the License after 7 days of the initial purchase.
All depends of the developer, but for example, we charge about $300 - $350 for a similar module.
Is some expensive because is a module developed only for you and not for public sale.
You can send a PM to PauloV another great developer for get a quote and have a second opinion.