I have a research microscope, and when I first started, I was finding everything under the sun. Problem is, most were normal artifacts. And when you do find something interesting, it could be just passing through. There is a lot of experience that goes into this, but I don't want to discourage you if you want to pursue this discipline.
Giardia is very distinctive and easy to identify, and they can be motile. Staining is to make conclusive evidentiary finding. The visual inspection should suffice for the purpose of convincing your doctor to run real tests. Or, there are plenty of private labs that will do this for probably less than the price of the equipment you will purchase.
Giardia is an easy ID in my opinion, if the infection is acute. You could even grow the cysts in the right medium, from stool sample if nothing is found immediately.
Unfortunately there are other parasites that are far more difficult to ID, and these are the bulk of what brings people to these forums.