E-Learning Platform Developer Needed

I want to launch an online learning platform to sell courses through videos, quizzes, and certificates. The main requirements are a learning management system with progress tracking, course sales with integrated payment, and a simple interface for managing and adding content. I’m open to WordPress, another CMS, or a custom solution, and I’d appreciate recommendations based on your experience. Please share your profile, references for similar projects, and a timeline and budget estimate for your recommended approach.