I've never used it myself, but understand that it's THE way to go for large purchases and/or higher risk purchases.
For small amounts where seller integrity is a concern, I've heard that using a US Postal money order (NOT a bank money order!) is also very good, as it's considered a governement-issue instrument. Thus if the deal goes south, the feds are much more likely to step in and investigate the issue.
<If you're gonna be dumb, you gotta be tough>
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