eh you won't get into the dslr game for that money,you'll get a nikon d-50 new for about 650/700 but thats with a very short range,rather flimsy lens
i'd look at the canon powershot s3 for that money,6mp 12x zoom,it's got an ultrasonic,image stabilised lens
the thing to watch with aerial shots is that unless you tell the camera otherwise it will meter the light levels off the sky in the background,making the aircraft look very dark so set the camera to spot meter in the very centre of the shot and be acurate with getting the aircraft dead centre frame,this is tricky with a moving plane and the lag on a digital,so look for something with a good burst frame rate and a fast focusing lens
ignore the megapixel race it's silly! 5mp is ample once the camera has a good lens in front in the firstplace