You got some pretty nice stuff here I personally wouldn't do a safe auction but that's only because I don't have a well-known, often visited shop. If you do a safe auction, make sure you advertise it well.
#3 will pull in more than 400m, honestly it could be well over that. It really only depends on the interested parties. If you find people that are rich enough and want the item, then you could possibly see around a platinum.
People like to say "it's worth what someone pays for it" but that's not really true. If someone rich enough wants an item then he'll jack up the auction to get what he wants. Now was the item really valued at what it sold for? No, someone just threw coins at an item until it was in their possession.
With all that being said what these items are valued at and what you may get for them are going to be different.