Eggplant seed is pretty easy to save- you use a blender! Sounds awful to use a blender, but it works well and makes it so easy.
http://www.rodalesorganiclife.com/ga...de-seed-saving
Cut the ripe eggplants in half and pull the flesh away from the seeded areas. If you want to save more than a few seeds, use a food processor or blender to mash the flesh and expose the seeds. Process (without peeling), and put the pulp in a bowl. Add water, let the good seeds settle, and then pour off the water and debris. Repeat until only clean seeds remain. Add a bit more water and pour the mix through a strainer with a mesh fine enough to catch the tiny seeds. Dry the bottom of the strainer with a towel to absorb excess moisture and dump the seeds out onto a plate to dry.