Missing Costume level 4

http://runescape.wikia.com/wiki/Costume_room/List

Highwayman mask
Cat head - 2m
Ranger boots x4
Robin hood hat x4
Top hat x4

===Level 4===

Black dragon mask - 7.5m
Frost dragon mask - 3.5m
Bronze dragon mask - 1.7m
Iron dragon mask - 1.6m
Steel dragon mask - 1.5m
Mithril dragon mask - 1.5m
Ornate amulet of fury - 16m
Ornate dragon armour - 93k+1.4m+1.4m+56k+set
Spiky dragon armour - 50k+37k+200k+30k+set
Armadyl rune armour - 1m
Ancient rune armour - 1m
Armadyl blessed dragonhide - 2.2m

Infinity robes - 10m

Milestone cape 80
Milestone cape 90
Spirit Cape