Can I buy Reddit karma? Is there any way I can buy an established Redditor's account?

Yes you can buy Reddit karma:

• The majority of KARMA buyers utilise Bitcoin (BTC) or Ethereum to make their purchases (ETH). While Coinsquare does not let you to buy KARMA directly, you can use it to buy Bitcoin or Ethereum, which can then be used to buy KARMA. 
• 123accs can help you drive a lot of traffic to your website, and as long as you keep your account active with high-quality posts, there's no reason why you can't be successful with 123accs Reddit accounts.
• When clients come to ACC Farm seeking for Reddit accounts, they want to be able to obtain high-quality solutions that, in many cases, will provide them with immediate delivery and round-the-clock service.
• They offer a chat window where you can simply contact them regarding any of their account options, and they have assured you that everything they do is completely secure.

Read More: How do people make money by karma farming on Reddit?