There are some fantastic portrait lenses out there for cheap, if you know where to look. A great example is the Jupiter-9: a 50-year-old M42 mount 85mm f/2 Soviet lens that, in the right hands, captures beautiful portraits with gorgeous bokeh.
It may not be the first place that comes to mind, but the Soviet Union is a great place to start if you're looking for a good quality piece of glass on the cheap.... well, what's left of the Soviet Union anyway.
After using a vintage 1910 lens on a modern Sony a7II, Paris-based photographer Mathieu Stern is back again with another interesting lens experiment.
This time he created "bokeh madness" by attaching a Russian Jupiter 9 85mm f/2 lens onto his Sony a7II using a M42-to-E tilt adapter.