I notice your avatar is a horse, do you have horses that get mansonella?
The microscope I've had for about 4 years came from Ebay... It's a fairly good one,(I think), a compound binocular that came w/ a camera(I broke), and separate monitor that I no longer even use. It has served it's purpose for me... which was prove to myself that there really was stuff going on and I wasn't a complete whack!
I am strictly an amateur though, so wouldn't be able to give expert advice on what to purchase, but here's a couple links to try: