Forgot to say one thing.
Of the sixteen or so varieties I have, I think I've only purchased one or two. Since these plants multiply fast, it seems you can always find people who are willing to do trades. Some of these plants can be kind of expensive to buy.
I've also found that there seems to be a lot of crossover between ariod people, orchid people and carnivorous plant people. I've done a lot of trades of orchids for either of the other two. Once you have a few of the more uncommon EE plants, trading becomes even easier.