A team of physicists and engineers at the University of Strathclyde, in Scotland, working with a colleague from the University of Glasgow, has developed the means for 3D printing a microscope, including the lens, for under $60. In their paper posted on the bioRxiv preprint server, the group describes how they came up with the plans for the microscope and notes that the end result has a resolution strong enough to make out individual blood cells in test samples.
One gets the impression the printer necessary for a lens eats the cost difference.
As 3D printers become increasingly commonplace, I have noticed various ways of accessing a 3D printer without having to own one — my local library has one nowadays