In reply to nocones:
Unlike what Nocones says about doing the transaction at your bank, do the transaction at the buyers bank
The buyer bank will release the money if the money really exists. If the bank hands you a check then ask to cash that check right there at the bank so as to walk out with cash. If you do the transaction at your bank, the buyer may still bring an official looking check that could still be crap and when your bank figure out in two weeks that it is crap they will then reverse the money out of your account.
Things vary by state but my last purchase went like this.
Agree on price in driveway on Sat morning (not a dime in my pocket.)
Seller and I drove a few miles to my (buyer) bank.
I withdrew the cash for the seller and had the teller complete the notary of the title right there.
If the seller is willing to pay in cash and that much cash makes you nervous then meeting at your (sellers) bank is good.
The buyer can walk in with a stack of cash and you can fill out a deposit slip right there. Real money with then be safe in your account with no risk to you as well as a comfortable place for the buyer to pull out a wad of cash.