I got an Omax microscope on sale on Amazon some time ago. It is a compound microscope with 100x oil immersion objective, which may be what you need for fungal spores and such. I’ve been very happy with it. If I remember correctly, it was less than $500 with a couple of accessories I got along with it (such as a stage micrometer to calibrate rulers). It has a USB camera that plugs into a USB port on my PC or laptop and that turned out to be very convenient for teaching online as I could switch to microscope live view during class meetings simply by changing the camera in zoom. It can also of course be used to take digital pictures, either with the software that came with the microscope or directly in Photoshop. As an example, here’s a moss observation where I used the microscope to look at spores.