No, don't buy gold because:
1) Gold sellers compromise accounts, vendor all gear, and ship the gold off - mailing it between numerous accounts to make it 'harder' to track (ie they launder it)
2) They will delete your toons and make their spam bots. Yeah, those toons "Ajlkjfdf" spamming in trade for their gold selling website? Someone's compromised account being hacked and manipulated, until its banned because of spamming. That's why a lot of times folks will try to re-acquire their account, only to have it banned by blizzard for suspicion of gold selling. This can be confusing for players who have been hacked, because of course they were not selling gold. But the people who hacked their account were. Even if 1000 people ignore the spam bots, it only takes 1 poor sap to go to their website and they move on to the next victim. Rinse, repeat.
3) Z-axis exploiting farmbots: They travel under the terrain, harvesting nodes. You can't always see them, but sometimes if you stand around a node in a remote place like say Storm Peaks, you'll see a toon "pop" up from under the terrain in an erratic fashion, and the node will disappear. They do this to avoid mobs and make harvesting nodes as quick as possible. It's the same exploit goldsellers used to spell their website's name with corpses in capital cities.
So in the end you can safely assume probably about 99% of all gold people buy online has been acquired through illicit means, and, more often than not, will simply lead to your own account being compromised.
Get an authenticator for your account, don't buy gold (its sooooo easy to get now at 80 for all your needs... ever hear of a GDKP run??). Also, I suggest
No-Script if you run firefox. I can't speak for any particular Antivirus software, I just use AVG free.