Actually, the cost of a new copy of Oregon Trail II is pretty low. Look on Amazon and get yourself a copy of the 25th Anniversery Edition, which includes some bonus historical versions in addition to OTII (you get the DOS version similar to the Apple II edition, a DOS game that looks like the first Mac version, a Windows version of the original, and the old Mac version of OT). You may even get lucky and find a used copy from 1996 that has the Prima strategy guide with it! (This guide is even better for historical purposes than for playing the game...I got good at OTII from it and also gained so much history from reading it).

I still recommend OTII to people looking for an OT game because the versions that followed put too much emphasis on little things and not enough on the history.