well, newer cameras are forcing them cheaper.
and manufacturers have come out with cheaper cameras so they can capture the low end. trust me, the better cameras start higher.
one way manufacturers save money is to use a cheap plastic shell. or even a good hard plastic shell, as opposed to metal.
another way is to skimp on the optics.
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prosumer cameras start at $600.
low end pro starts $1000. high end pro starts the same as well, but the accessories bring the price up. start with the body of the camera, then add thousand dollar lenses... etc...
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don't forget that memory and batteries add to the cost.