I agree, this unfortunately does happen sometimes so it pays to do your home work.
My advise to you (@75kg) is to get either a 11 or 12m kite for lighter winds while first learning and then you can add a smaller higher wind kite later, obviously if your learning in a high wind area use a smaller kite.
For a first kite you can't go wrong with any of these 2010/11 models:
Cab Switchblade
Naish Cult/Bolt
Slingshot Rally
Ozone Catalyst
Best Kahoona
North Rebel
Good luck mate