Cheap:

Common profession materials (elementium, obsidium, herbs, cloth, hypnotic dust, etc)
Glyphs

8 different Bags filled with 333 ilvl sets for:

Strength plate dps
Strength plate tank
Int plate healer
Agility leather dps (includes both thrown and relic)
Aglity mail dps (includes both relic and bow)
Int cloth (no spirit gear)
Mail int
Int leather

9 different Bags filled with 333 ilvl weapons:

2 Strength Swords/Axes/Maces
1 two handed Sword/Axe/Mace
1 strength sword/axe/mace and 1 shield
2 Agility Axes/Maces/Fists
2 Agility Daggers (slow and fast))
1 Int Weapon and an offhand item for cloth casters
1 Int Spirit weapon and an int shield
1 Agility Polearm/Staff
1 Fast Agility Dagger and 1 agility Axe/Mace/Fist/Sword (maybe ignore this one as it's only used by one spec of one class


Average Price:

Uncommon and Rare materials (Celestial essence, Heavenly Shards, Pyrite, etc)
Cut Rare Gems
BiS Enchant scrolls that don't cost Maelstorm crystals to make
Ebonsteel Belt Buckles

Expensive:

Epic BoEs that can actually be obtained normally
30 different bags filled with a full set of 346 gear, hand picked BiS for each spec of each class - I wouldnt include trinkets in this
Epic Materials (Maelstorm Crystals, not sure that there are others)
Expensive enchant scrolls (Landslide, Power Torrent, etc)
Valor Points (respecting the weekly cap)
Charhide/Dragonscale Leg Armor
Powerful Enchanted/Ghostly Spellthread
Rare Profession Patterns