Oh, don't worry, it's perfectly safe to buy them 
online, especially from any of the larger dealers 
such as those listed at Cels.org's Keep Track.  
The major problems come up with private sales or 
online auctions.  In those cases, just proceed 
cautiously--it's not at all out of line to post a 
message here saying "Hey, is Joe Q. 
Dragonballseller a straight shooter?"  Ask the 
dealer questions if you've got them, and if 
they're evasive or such, write 'em off.