The Cloudflare pricing model is tiered, with different prices for different plans. CloudFfare doesn't bill for bandwidth usage, and you can upgrade or downgrade easily between plans.
Cloudflare Free: - Speeds up your website, offers broad-spectrum security protection, and provides useful statistics about the visitors to your site. Free
Cloudflare Pro: - With this solution, your website will perform faster and you'll get insight into what is going on with your site, as well as SSL, mobile optimizations, web application firewall, and real-time stats. $20/month for the first website; each subsequent website is $5 per site/month
Cloudflare Business: - In addition to all Pro features, you also be given the ability to customize fully. There is a 100% up-time guarantee, Railgun web optimization, advanced denial of service attack mitigation, and more. $200/month per website
Cloudflare Enterprise: - This plan has all the Business features plus a setup consultation, 24/7 phone support, dedicated account management, an SLA of 2500%, and more. Average price is $5,000 per month (need to call sales for an accurate quote)