Shopify Setup with Booking System Integration

I need a developer who knows Shopify inside-out to add an appointment-scheduling system to my store. The key requirement is reliable Google Calendar sync so every new booking instantly shows up in my business calendar and any changes propagate both ways... (Budget: $2000 - $6000 HKD, Jobs: API, Booking System Development, HTML, JavaScript, Shopify, Shopify Development, Social Media Marketing, Web Application, Web Development)