Yes, the SE comes with the 3rd game, which is only available physically with the SE. But it is cheaper to get these with the 30% deal. The 3rd game will apparently cost $20(USD?) if you possess any other version. So to get them separately costs something like $35 + $35 + $25 = $95. The SE is $80USD, seeing the exchange the $60USD Zelda SE got, it could cost anything from $110 to $150 for us...
You can always cancel your preorders. It's easy, it's just a checkbox to nuke a Amazon preorder, and Amazon price protects so any price drops affect you preorder +30% (even price errors, somebody mentioned Xenoblade dropped to $20). So order every single game you think you might want, and decide if you want to cancel them later when you're sure.