I personally don't like it when someone selling something _needs_ to talk to you on the phone to make sure you're legit.
Chill, people, if you don't get your money, then just don't send me anything.
Once, I remember emailing someone from the Buy/Sell forum, but he said that he had already sold his part. "Still," he says, "one of my friends is parting out the same bike."
I emailed the friend, sent across paypal, and got huge boxes of delicious parts in the mail (yes, I'm a monster, and I eat them).
The money coming across first is what makes you trust a buyer, not how they contact you. If you're internet-paranoid, use eBay - that's why it's gotten so bloated and expensive.