Thanks all!
Citrus are not really difficult to grow in Switzerland, but you need a special fresh place (orangerie) during the winter to grow them. It's easier as true tropical trees due to the fact they have training to variation of temperatures, which is frequent in the Alps.
I will probably send by post the biggest ones (as my C.hystrix which is 2m tall) and the smallest rarest ones I'll bring them with me bare roots. But before to try to carry them bare roots, I will try to graft them and bring with me only scions. For the most common ones as lemon, orange,... I will sale them, because I can find them here also.