Dear, Employer! In my opinion, I can build your site with database and comfortable user interface using Django and React. To be specific, I wanna make data base as you required like name, address, price, etc. Then using gmail, send the total price to customer. At this time all data is stored in database. Second and third agenda are not problem, I mean, it is fundamental process of web app. Finally, using pythong package, any data you want can be converted to Excel and csv or versa. I know what you mean, if you hire me, I can finish this project as soon as possible. Thank you.