As a full-stack developer with over a decade of experience, I am confident I can create the PHP script you need for your estimate generation system. With a solid understanding of PHP and its core functionalities, I have completed numerous projects leveraging this language while meeting tight deadlines. My speciality lies in building robust web applications that are not just smooth and efficient but also password-protected, scalable, and easily transferable to another domain - exactly what you are looking for!
In my previous work, I have extensively utilized SQL databases for efficient storage and retrieval of large amounts of information. This would be invaluable for your project requirement to store client information, allowing easy access through multiple search criteria. Moreover, my proficiency with API integration will enable me to integrate seamless payment processing using Stripe.
Furthermore, my skill set is diverse - proficient in ReactJs, Nextjs, Strapi, NodeJs etc., making me versatile enough to meet any design attribute or business logic specification you require. Lastly, rest assured that choosing me ensures not only the creation of an excellent product but ongoing support including bug fixes or updates; all aided by clear communication and adherence to your budgetary needs. Let's build a high-quality estimate generation system together!