I realize this thread is for 2010 Samsung Plasma buzzing, but I have a 2009 model that I purchased (manufactured in Jan 2010), and it does indeed buzz. I definitely would purchase it from a place that has a good return policy if you are concerned. It bothers me a little bit, but I usually just forget about it, and I don't even hear it. It's not super loud, but it's definitely loud enough if I focus. The picture quality makes up for it. I personally don't think it buzzes abnormally loud.
*All* plasmas buzz and all people have different abilities to hear the buzz. So, you really shouldn't buy a plasma if it is going to bother you.
I will guarantee you one thing. The more you read threads on buzzing, the more disinterested and frustrated you will become with your TV or soon-to-be TV.
So, my advice: Buy it, return it if you absolutely hate it, but otherwise... suck it up and enjoy the great picture.