My solution was: select out few bricks (pencil cup/ unused parts: overall 2trays). I bought this “grandma trolley” + some boxes. Connect them with a hook. This package was below the limit: https://www.dropbox.com/s/8tefqzsmunebzwd/2015-03-16%2018.06.55.jpg?dl=0
On the airport I used this plastic foil what they provide. Worked for me, but depends. Important part is to buy a trolley which has wide enough wheels. A foldable one is better. I only brought 10 bags of small kit. Also good thing to put the bricks into plastic bags.
BUT nowadays I’m thinking on changeing the system:
1. http://www.auer-packaging.de/de/eurobehaelter-koffer_51.html
pro: strong, standard size, modular. You can buy inner trays and boxes as well
con: too heavy (1.5kg/ box)
2. IKEA system:
pro: lightweight, different sizes, cheap, easy to get another box.
con: LEGO trays doesn’t fit, you have to use different one. Can’t lock the boxes. Not that strong. No lock/solution to close the top, so you need to use a tape or so.