There are several exchanges that offer CKB buying & selling services!
Some of the most popular exchanges are KuCoin, Huobi, Gate.io, Voyager, Crypto.com, Changelly, and Binance.
Although, availability on these exchanges does depend on your region, so if one does not serve your region, make sure to check another!

Global users prefer Binance or Huobi.
USA users can refer to this guide: How to Buy CKB in the US

Check out these latest guides for all exchanges supporting CKB: