Build me a website

I need a website that shows a list of offers of different products with their prices, and the offers must have a validity date and quantity available, so they should be deactivated when not valid or not available anymore. When a client is interested in the offer, the client will click the “BUY” button and we’ll receive their inquiry in a backend website so I can keep track of their demand. Only registered clients can click this BUY button, otherwise it will display an alert when clicking that the user must register to proceed.