What do you mean by saying: they wil insure you? do you mean to say that they will compensate you?
usually airlines have a limited liability of about 20US per Kilo. So even if you can prove that the bags contents are much higher in value their liability end at the rate advised. Every compensation which is higher is a so called good will, it is not compulsory and some airline do it just out of a customers service perspective. In Any Case a final compensation usually takes more than three months as to be sure that the bag got def. lost. Try to get an advance payment if you are not in the country of your origin as to buy basis stuff. Let them clarify to you what their policy is.
One thing you should do is submit a list of the contents, a very details one.