Hey there smonline, good question!
Most people around here use PayPal for smaller and medium transactions and some use Escrow.com for larger ones.
It partly depends on if you know the person you are dealing with! My advice is.. get to know a few people around here! Buy a few domains, swell a few, and network.
As you do more business and post more, people will grow to know and trust you more!
Hope this helps!
WebCat
/\_/\
(0 0) Meow!
>^<
\__/