It's still high because they are still making money from it. Games are still coming out for it. MKX, MGS:V, Battlefield:Hardline and most of the big titles from the last holiday season were also ported over. Once developers find it cost prohibitive to develop on the 360 due to lack of interest then the price will hit rock bottom. So expect a price drop next fall.
I'm a fan of Citizen Kane, although if your young then it's hard to see the cultural impact it left behind. Imagine how amazing something like Shadows of Mordor would be if Batman or Assassin's Creed did not exist. CK serves as a demarkation between how movies were shot and how they are shot now. Movies prior to CK felt like stage productions. The camera was passive like an audience member. CK not required watching these days unless you are a film major or you want to learn more about the history of cinema. But it's still a good movie although harder to digest the younger you are.
I think the best way to tackle this list would be hitting the titles who's impact may be waning the most. You want to encapsulate the excitement of playing these titles while they are still relevant and ideas/mechanics not lifted into dozens of others titles. I.E. Jumping into Assassin's Creed will muster a luke-warm response after playing Batman/Shadows of Mordor. That being said, start with Bioshock. It still holds up quite well, also I would consider skipping 2 entirely as it only feels BioShockesque ( I know, not a popular opinion) and going straight into 3. You have lots of good titles ahead of you, go have fun!
Also Chrono Trigger is timeless. No rush to hit that anytime soon.