At the moment, there is a trinocular Nikon SMZ-2T with a dual-arm boom stand, for sale on ebay, at a reasonable price, from all indications, a reputable seller. It includes a ring light and should just need an 0.5X or 0.7X auxiliary lens (which you can also get off ebay) to become an excellent microscope for SMD work.
The microscope is from the 1980s and was built to last. It is much more solidly built than the great majority of 'scopes you can buy from the "big four", and far better made than anything out of China. My father has one which he has heavily used for decades – that I fully expect to use when he is done with it, and I expect the next generation will use after I am gone.
Being 30-35 years old, it may need some cleaning and lubrication. If you can budget, say, another $150-400 for that, you will have a really good microscope that will likely outlast you.
Anyway, I thought I would mention it.