I just bought a suzuki z400 for myself and a honda 250ex for my wife but at the dealership they told me to have the honda's valves adjusted on the break-in oil change, is this true? and if so about how much will it cost me.

 

If the valve train sounds quiet to you, blow it off for an oil change or two if you want. About the only time I see valve adjustment cause any problems is when somebody sets them wrong.

 

You might want to buy a sevice manual and learn how to do it yourself, in the long run, its the cheapest, and you also have the satisfaction of knowing more about how the motor works and is adjusted.
Its not tough to do.