You can build a CDN on top but if you just need basic CDN features then you should probably look at something else. Cloudflare allows purging all of the content, or individual URLs, for free through the UI or API. You only need enterprise for the more advanced tag-based purging. You can also look at Fastly which is another configurable CDN. BunnyCDN is also good. Start simple and then move as you need more.