The cost of building a WordPress theme can vary widely based on factors like complexity, design, features, and developer rates. Basic themes might start around $500 to $1,000, while more intricate and custom themes could range from $1,000 to $5,000 or higher. Premium or highly specialized themes might involve costs upwards of $10,000. It’s recommended to discuss your specific requirements with a developer to get an accurate estimate tailored to your project’s needs.