sister is after a good camera to use to take photos of her work, which is a good camera that can take professional looking photos for less then $500
pritty much know nothing about camera's and she has been using her android phone so far and wants to take better quality photos for her site.
Key to taking good photographs is to understand and have the ability to adjust the different aspects which when combined will give you the perfect exposure.
A DSLR should help you achieve that.
However, point and shoot cameras do take some really good pictures. But has limitation related to what and when you are taking pictures of.
If you could tell us what she would take pictures of, we will be able to guide you better.
Cheers.