Deciding on EMC values would really be a bitch. It's even harder then it looks like at first glance. What about EMC values of something like the old uu-matter? (just cause' I haven't touched the new version yet) It cost scrap, so you could say x scrap = one uu-matter. However, uu-matter also costs energy, so you'd have to find a way to balance that. And even then, you'd need to add extra EMC for skipping right over the mass fabricator, and all the over machines you'd be skipping over to get that mass fabricator.