Things that COULD be included into the tiers:
Common: Small EXP Lamps for all skills, Noted Ores/Logs (25 for anything including and below Willow/Coal), Random throw-away items like Buckets, Pots, Feathers, Bronze equipment.
Uncommon: Medium EXP Lamps for all skills, Noted Resources (25-50 a piece for anything including and below Yew/Adamant), Medium Tiered armor like Adamant/Rune pieces, Random Runes and amounts, maybe even the cosmetic helms/tattoos.
Rare: Large EXP Lamps for all skills, Noted Resources (50-100 a piece for anything including and below Magic/Runite), high-end armor pieces such as GWD Boss/Dragon, Weapons such as Whip, Godswords, maybe even venture to see if the Lucky variants of these pieces, or Barrows pieces, are available.
Super Rare: Huge EXP Lamps for all skills, Custom Items, INCREDIBLY hard to obtain items (maybe Nex or other boss drops), Cosmetic Items that are impossible to obtain otherwise, see if the Skilling Outfits (Blacksmith, Angler's, etc) bonus exp outfits are available in-game and add it to this category.
All items are simply suggestions. Rates at which to obtain the items are at the whim of developers (Justin) and even if they're added would be up to him. But, I would like to see the re-vamp done and would like to see the ability to get things other than common/uncommon items, but wouldn't want it to be overly powered, either.