There are many options for taking photos through the eyepiece of most microscopes, including smart phones and a number of inexpensive cameras that can be found on eBay or other websites at a very low price. We do not handle any of these but encourage you to go directly to those sources for inexpensive imaging.
For professional imaging we recommend dedicated microscope cameras such as the Zeiss Axiocam series or generic dedicated cameras on Trinocular microscopes. The advantage of these cameras is that they are connected to your computer for a live, on-screen preview to ensure proper focus and composition as well as providing extensive lighting and color adjustments. Additionally, most come with software that will calibrate the camera to your microscope so that scale bars and measuring functions can be incorporated into your images as well as annotation of your images so that you can document exactly what you were taking a picture of.