You might be able to find a collector on ebay for the Nvidia RIVA and the Cyrix M2. Other than that I don't think these parts are anything but junk now. Definitely not good enough to be used for it's purpose anymore.
It is not work anything. Too slow and obsolete to be of any practical use today.
Perhaps if it is in excellent condition and you can find a electronics collect it might be worth something. But how many people like that do you think there are? And how hard do you think it would be to find someone like that?
Not plastic, FR4 fiberglass-epoxy mix or equivalent. On some motherboards, even PCIe connectors are made of the stuff since it is stiffer than plastic and does not soften as much with heat. Chip encapsulation is often epoxy too.
The most valuable thing on a PCB is probably the copper for places that have equipment to process that. The simplest process involves grinding the PCB and whatever may still be attached into sand-like bits then use specific gravity to sort it out - heavy stuff goes down, light stuff goes up. Each layer ends up containing a relatively narrow range of materials which can then be sent out for further processing/refining.