Grargar: It doesn't really matter if Ubisoft is here. The games aren't even on Steam, so more than likely, neither of the two parties find it worthwhile to come to an agreement.
Yeah, I guess. What would hold it back though? Ubisoft and Cyan not agreeing on how to split the profits from selling the game? I can't think of any other reason they wouldn't throw the games up there and see what extra money they can get from it.
Grargar: Depends on whether you are looking for it used or new. It's easy to find a cheap used copy on Amazon.co.uk. New copies are kinda expensive (over £15), but nowhere near the 100s.
I was specifically looking for the DVD versions, and I do remember them being really expensive new. Now it looks like they are available used fairly cheap and the new price has dropped too :D For example I looked up the version of the game that I already have, which is the DVD special edition of Myst IV that also contains Myst III on DVD, and it's $70 new or $30 used (I really remember that being around $200 last time I checked for it). And then other versions of the games are a lot cheaper, in the $10 range used, but they're probably on CD.