LocalBitcoins is a P2P Bitcoin exchange. Buyers and sellers agree on trade terms, and LocalBitcoins is used as escrow. LocalBitcoins is one of the most private ways to purchase bitcoins. Fees can be slightly high when buying with cash, since many people are willing to pay extra for the privacy. Be warned that scammers do exist in this space, so be very vigilant and verify everything when making a transaction with someone you have never met before.