we discussed something close to that in the mod chat
I'm not really someone who is familiar with SM, so feel free to fix me on things that I got wrong. But here's the summary:
1. there will be different item boxes, and there's a level that goes with each one, lvl 1 and lvl 28.
2. lvl 1 item boxes will be available to all players no matter wat kind of level he is, and it will give the under-lvl-28 hidden items.
3. lvl 28 item boxes will only be available after the player reaches lvl 28, this will allow players to get the over-lvl-28 hidden items.
4. the lvl 28 item boxes are, obviously, more expensive than the lvl 1 item boxes. But I'll leave the price for those who know more about the game.
This way, it is in no way different from the current system, where only those over lvl 28 can get over-lvl-28 hidden items, but add in an ability for them to get under-lvl-28 hidden items for collection purpose.
btw on the topic of item boxes, I suggest calling all rare, legendary, etc hidden items like I'm already calling
and over-lvl-28 hidden items will be called high tier hidden items, and the other will be low tier hidden items