Now, if the bag gets delayed (i is regarded as delayed the 21 fist days for AF, and 45 first days for KLM and DELTA), you are allowed to go out and spend necessities. Just remember to keep all invoices. You can do so from the first minute the bag is delayed, and you can also do this on your return flight home. But it MUST be dated before you receive your bag
When you call them, they will say that you are allowed to spend 100E per person involved, but that is just to make sure people dont go shopping like crazy. IF you DO have invoices for 800 Eur, you will get them covered in any case... (well, not computers or other things that should not be check in in the first place)