I recently completed two transactions using what I consider large amounts of cash. One as a buyer and one as a seller. Both were out of state. It is a little concerning when traveling with large amounts of cash. After several conversations with both people, I felt confident that they weren't out to rip me off. The buyer came from out of state. He contacted his bank and told them that he needed to pick up X amount of cash in a different city. They had it ready for him when he got here. He said he was a little nervous driving the 30 minutes to my house.
BTW the IRS is only interested in DEPOSITS of $10k or more. You can withdraw all you want. The law was made to catch people depositing cash from drug deals.