5.5k doesn't seem like a terrible price, but unless you are either...
1) Rich beyond your wildest dreams; or
2) Missing that one slot and are in a very aggressive, progressive raiding guild; or on the flip side
3) Will never ever see the inside of a raid, so this is the best chest you'll ever get
...unless you are any of those things, I wouldn't buy it. If you're in a casual raid guild, you'll eventually see better stuff than this (mastery>haste>crit, generally, and this thing has crit) and it doesn't really matter if you have the absolute best gear you can get since your guild isn't pushing content boundaries anyhow.
On the other hand, gold, eh, you can't take it with you. Spend spend spend! ;)
____________________________Mccready | 85 Human Rogue | Argent Dawn
Rubmyhorns | 80 Tauren Druid | Bleeding Hollow
Giventofly | 82 Dwarf Paladin | Argent Dawn
Ayn | 82 Human Mage | Argent Dawn
Sevendeuce | 71 Undead Warlock | Bleeding Hollow
Nyadnar | 70 Orc Warrior | Bleeding Hollow
Outofideas | 56 Troll Hunter | Bleeding Hollow
Killphilip | 44 Undead Priest