• "Abandonware" — IP held by a company that wants to just sit on it and never release it again, and probably forgets it exists. Probably the company that produced the IP was acquired and shut down by the company currently holding it. It's nearly impossible to find a physical copy of most of this kind of stuff. I'm not a collector; I don't want to pay $1000 for the only surviving copy of some old book or NES cartridge or whatever. (Or, rather, I would, but only as part of a group-buy with the goal of giving the thing to a digital archivist who will properly preserve it and publish the results to everyone.)

• "Isolationism-ware" – IP that only legally exists in some particular markets. Usually meaning "some Asian country, and no English-speaking countries." To acquire such, I'd—at the easiest—have to convince the iTunes Store that I have a credit card with an address in that country; for the more indie stuff, I'd have to find someone physically in the country willing to go be my proxy, searching used book-stores/record-stores for the item and then sending it to me. Either way, I'd then have to work pretty hard to consume the thing, given that I don't fully understand the languages involved. Translated release groups handle all these steps. (I wouldn't mind if I could donate money to them in a way that would in turn give money to the original IP owner; I've just never heard of such a setup.)