Some do buzz, but it's hard to say how they will be until you try them... Can't really recommend any particular type since you probably won't have the same selection there as we do here.
I have a couple of noname 80W max electric transformers that cost less than 20 euros a piece. They are practically silent, the Innovus dimmers that control them make more noise...
The good thing about low voltage (12V) lighting is that you can legally install them yourself. That doesn't rule out using common sense, though - the currents are actually much larger than with 230V, and bad connections or too thin wires can get dangerously hot. As do the light fixtures themselves - 60W is still 60W, even if the bulb itself is small.