PLEASE HELP! -looking for used microscope objectives. (Bit harder than I thought)

I am trying to find 1 4x objective that is a plan fluorite (or better) and the same for a 10x. I am viewing geologic thin sections.

Thought maybe there has to be at least once person who has some spares or has some ideas on where I can find some for cheaper than retail. They need to have a 20mm diameter. I would love to find a 2x as well but haven’t ever found plan fluorite for 2x while searching the internet. The total price for buying these objectives would be like $1,500 plus taxes and shipping. Hoping to find someone who can sell some used ones vastly cheaper is able.