What is the difference between these cameras?
Example: the Nikon D3300, D5300, and D7100, all vary wildly in price
the 3300 is cheaper while the 5300 is considerably more expensive and the 7100 is way out of my budget
why such a wide range in prices
is the D7100 that much better than the 3300?
It really depends where you are with your interest… Cameras are aimed at different markets… The D3300 is aimed at the newcomer someone who wants great image quality and isn't sure whether they will go to the trouble or expense of adding extra lenses to their kit.
The D5300 is still aimed at the entry level end of the market and has some tweaks in the specification to tempt more experienced photographers… I actually use a D5100 and i've been messing around with cameras for over 40 years.
The D7100 is aimed at the enthusiast, someone that knows their way around a camera already… Or… The beginner 'newbie' that knows they are going to throw some serious time and money into their interest. The D3000 and D5000 series cameras don't have on-board focussing motors and this restricts the lenses that are compatible with the cameras… You will only get 'autofocus' if you mount the AFS spec lenses. The D7000 series cameras have an in built focus motor and this gives you access to a wider range of lenses… You can also mount and meter with manual focus lenses which is a huge plus for me… I only shoot in manual focus. The D7100 also has twin SD card slots and this is another nice advantage for me… The D7100 is also weather-proofed and sealed against dust… And is constructed with much better materials than the D3000/5000 series cameras.
In all honestly you wouldn't notice much difference in image quality, a more expensive camera offers better performance, faster burst rates for continuous shooting, improved buffer, more autofocus points, more accurate and faster autofocus… And you'll have actual buttons for regularly used features to save you from having to make changes using the menu options which can be a bit 'fiddly'.
I have the D5100 and it's a great camera, it's fun and it delivers great quality, I also have the D7000 and D7100 and the D7000 is the best camera i've ever used… I had a bad experience with the D7100… It's OK now… I just prefer the D7000 though.