Didn't expect so many answers. Unfortunately, I live in Romania, so the customized mailers/prepaid mail/other local systems won't work for me. I need someone who can receive orders from abroad and who ships internationally within the EU. I could, for instance, send a package with the films and receive the same package with them developed.
Thanks anyway, I will look into the options already presented. I know a few others who would like to do E6 but are scared because oa a lack of processing, so if I find a good lab with decent prices I might even offer this service commercially at no added cost