The cost of Exchanging $50k Walk me through buying 50k in BC using cash in Dallas and exchanging BC for cash in the SF bay area 3 days later. Specifically with attention  to costs and fees, and maintaining anonymity via in person transactions or whatever method is most relevant to maintaining anonymity.
If for cash means you want paper then it is possible only theoretically - you sell it in the same way as cucumbers or gas to the people that want to buy it. You just need to find them and it will be hard because if you don't want to do it online means you are afraid of something: fake banknotes, money laundering, etc.