Hangar on - I'm not remotely bitter, really enjoyed my time in, still have friends in and visit them.
I am however, realistic and it all has to do with entitlement.
Even if it is for charity, you will no doubt incur some costs - civ-air, ground transport, hotac, etc. The maps will probably be a minor cost.
Hope that you have a good trip to a very interesting part of the globe!
Stik