Buying a second hand PC budget around $700-$800 USD

Hi I'm trying to find a second hand PC between $700-$800. I play like CS and that's about it. Just want high performance and the possibility to stream. Are there specific specs I should be looking for. I understand the 3060 gtx ti is good that's about all I'm looking for. I also understand RAM is quite expensive so really capping at 16 GB. Any other tips or things to look for would be helpful. Thanks.