Doing large btc tx in person is very risky tho. If i'm a buyer i wouldnt meet some stranger with tens thousands $ worth of btc on me.
BTC is great for micropayments and online, digital tx. But until there is Bank-like bitcoin service (escrow) doing large btc tx in person is not for me.
I sold a car for $26K in BTC last year. I've also sold BTC for $4-5K cash on a regular basis back when I was mining "too much". Never once had a problem. Well actually, once somebody gave me 2 fake $20 bills, but that was it really.