Kevin Kelly has written about the Rosetta Disk — a Long Now project that has microscopically etched text in over a thousand languages onto a nickel disk, encased in a glass sphere. The intent is that it will physically last as long as possible, and also increase the likelihood of readability well into the future. (The disk is analogue rather than digital, and the microscopic nature is implied by text decreasing in size on the opposite side.) Provided that at least one of the existing human languages is still known, the disk should enable future scholars to read the others, as it reproduces several standard texts translated into the variety of languages.
(It’s not explicitly stated, but what might be the probability of a civilization with no prior knowledge of any of the languages being able to decode it, to some extent at least?)
Saving one disk for all time is pretty unlikely. The goal is to produce a sufficient number of these, and have them stored in enough different locations that one or two can be expected to survive. Total cost (as quoted by Kelly) is $25 000. Seems like a lot, if you’re considering buying one for yourself.
But compared to the sort of money that large organizations deal with, it’s hardly anything. Get enough people together, and it would be easy to buy as a group. I’m sure that any number of university libraries, national libraries and archives, and similarly large institutions will be able to pick one or two up without blinking.
And if I can find 99 other people to put $250 in, then no problem!