The plastic used in most model kits is polystyrene (6 in the triangle). I don't know how many communities collect this particular plastic, but would guess that not many do.
As for starting a recycling program, I doubt any of the companys would start one due to the relatively high cost of collection, shipping, and reprocessing compared to purchasing new plastic pellets. They may have an in-house recycling programs, but it's difficult to guarantee the quality of recycled plastics coming from an outside source... how many of your sprues have a little residual paint or glue from the construction process?
A local hobby shop could in theory collect and sell to a plastics reprocessor, though I'd be very surprised if it is as lucrative as collecting soda cans.
One of my professors (ironically enough for a plastics class) pointed out petroleum products (plastics and fuels) are simply combinations of carbon, hydrogen, and oxygen, and as such, the world will probably never run out of these products, it's just that the price will increase (A LOT).
If you've paid attention to the science headlines, you'll know that we can produce ethanol and some plastics from corn. A group has developed technology for harvesting and reprocessing material from landfills.
I'm not saying that the whole environmental picture is rosy by any means, but what's pumped into the air and dumped into the ground in liquid form concerns me much more than solid waste.