I thought about this, but after some research and experimenting the end result was less than satisfying. The plastic used for bottles is really different from the plastic used for discs. The process used for discs is very differnt from the one used to create bottles. The plastic is very brittle and stiff when it is remelted. It also out gasses some pretty toxic stuff when you melt it.
The molds are expensive to get made, and the equipment is pretty expensive. Injection mold machines like the disc companies use are huge expensive pieces of equipment. There are benchtop Injection mold presses, but they seem to be geared torwards making smaller parts. Heres a link:
http://www.injectionmolder.net/
Some one told me that Gateway has a Benchtop rig that they make putters with but I have never seen it in action.
Bio-plastics might be a option you might want to look at. You can make up some starch based plastics in your kitchen pretty easily. You can fool around with the plastics strength and flexibility by fooling around with the amounts of ingredients you use. Check this out.
http://www.instructables.com/id/Make-Potato-Plastic!/
I fooled around with this a little. Its hard to get the plastic to release from the mold, and you have to thermoset it. Its a cheap way to get started playing with plastics though.
I was thinking about making Bio-degradable minis so if you spaced them they would just biodegrade.
Good luck man. Keep us posted with your progress.