The bookmarking thing might be a show-stopper. I use a Sansa e250 .mp3 player and it will allow return to the same point in an .mp3 playback upon switching the unit back on, but it will not allow a bookmark for selected .mp3 files.

I'm assuming your wife wants to listen to a section(s) of an .mp3, go to a different .mp3 to a bookmark in that file, then return to the first one at the place she left off. Is that correct?

I'm pretty sure the Sansa series from SanDisk will not do this. They are some of the more reasonably priced .mp3 players out there