My first bit of advice: Find an experienced flyer local to you who can show you the ropes, explain how all fo this stuff works, etc. You will have a much easier and more enjoyable time if you learn some basic facts about the electrical bits that help these airplanes fly. Another RC flyer is going to be a FAR, FAR BETTER resource than the salesdroid at the local hobby shop.

As for your field box charger issue, you can power the thing from your car battery. A pair of large alligator clamps (open the hood, attach to the car battery) or a cigarette lighter plug should do the trick. If you want to do your charging indoors, you can pick up a 12V DC (nominal, most are actually 13.8V) power supply from Radio Shack or any ham radio dealer such as Ham Radio Outlet or AES. A small 5 to 10 Amp supply should be fine. A car battery charger will probably work just as well, and they're cheap too. But the cheapest route by far is just hooking it to your car battery long enough to charge your flight box.