Very interesting release, I'd surely buy it! I guess normal jewel case with space for four cds would be the way to go in your case. Special packaging can be nice, but as it was said before, everybody has seen their share of special editions and it doesn't turn any heads anymore. Plus I think that a lot of special edition digipacks are not thought through, for example the type used for Barzel - Born to Destroy Amalek or the latest Vomit Arsonist, where the cd is actually lying directly on the cardboard and you have to leave fingerprints on the underside of the disc and maybe scratch to get it out (happened to me with my copy of GO - Remember). Nice artwork and a nice booklet with songtexts and/or a good share of pictures are always a great incentive, maybe also a fold out poster or some other gimick? I agree with the moderate price idea, people simply like bargains. Don't know how low one could go without losing too much money, maybe something like 25-40 €?