Dynamic Pricing Webpage Development

I need a modern and sleek webpage to facilitate real-time product pricing for sellers visiting customers. The products are categorized into about 30 types (e.g., Glass Wall, Pergola, Greenhouse, Screen, etc.) with various dimensions and options.

Requirements:
- Password-protected access
- Grid of product images for product selection
- Ability to create a "cart" of selected items for real-time customer quotes
- Comprehensive backend to store all data, integrated with Google Sheets for easy price updates
- Clean and modern design for professional presentation

Ideal Skills and Experience:
- Proficient in web development, especially with password protection and Google Sheets integration
- Strong design skills for a modern, sleek interface
- Experience with dynamic pricing tools and "cart" functionalities