I really like the Pay It Forward system, and if traders get on board with that, it's a truly magnanimous way to trade. i.e. One person provides you a copy free of charge. Even the discs are free. Only obligation is that you turn around and make three sets available for free to three different people who are willing to do the same. Beyond that, blanks and postage will keep it getting out to more people. But the Pay It Forward system is the method that will most reward the entire community.
When you consider that single layer discs are down to about 40 cents a piece, this really isn't a big investment at all. That means giving away six dollars worth of physical product. Two stamps will cover postage, and you can make your own envelope out of a sheet of paper and packing tape. The package will be sturdier than anything Netflix ships in bulk every day, just because 5 discs tightly wrapped are generally pretty sturdy. And when you're giving the project away on an exponential level, it REALLY takes the demand out of the hands of jackers.
The cost of dual layers is, of course, a lot higher. I can't address it much beyond saying that if you can pay forward on two single discs to people with dual layer burners. It's a simple matter to assemble the files on a computer. For those without dual layer burners, once again, blanks and postage are a suitable method that many people will go with.
Sorry for such a cagey answer.