A Spanish company called Extreme Polymer Research has developed a line of polymer cases for a number of handgun cartridges and plan to bring them to market next year.
Unlike polymer shotgun cases, these cases do not have a steel base, they are entirely polymer. I asked the company if they have had any problems with the polymer melting or malfunctions in high temperatures. They responded in saying that the polymer selected for the cases is also used to build automotive parts and has been tested in temperatures ranging from -40 to +150 degrees celsius without problems. They tried some transparent polymers, which would allow visual inspection of the power load (and be very cool!) but these did not function correctly under stress.
The primary benefits of these rounds is consistent quality and pricing that is not dependent on the rising cost of copper.
Extreme Polymer Research will only be producing cases for straight-walled low-pressure handgun rounds (.380, 9mm, .40 & .45) because of the problems inherent with polymer cases necked rifle rounds. A few companies have tried producing rifle ammunition with polymer cases but they have all failed.
The ammunition will go on sale next year in Europe and hopefully the USA. The retail price in the USA will be in the 6 to 8 cents/case range.