The Warden armour is very common for levels between 60 and 90. Also it is a great armour for a cheap price.
How to Obtain 
You must be at least level 60 to start gaining these pieces of armour. Every 5 levels you will unlock the next piece in the chain. Starting from in this order - Gloves - Boots - Helmet - Greaves/Robe - Breastpate/Robe and Weapon
To start go to Stonevale Farm, and talk to the messenger by the mailbox. He will tell you to go to the druids by the Northern Peninsula in Lir's reach. Talk to them to begin.
The people will ask for discs. Every piece requires a combination of different ones. Every class needs the same discs for each part. Discs are obtained from otehr players or may be gotten from a drop from bosses such as Chillmist or Fellfire.
|Parts of Armour||Disc 1||Disc 2|
|Gloves||1 Sun Disc||1 Moon Disc|
|Boots||1 Oak Disc||1 Moon Disc|
|Helmet||2 Sun Discs||1 Elm Disc|
|Greaves/Robe||2 Oak Discs||2 Crown Discs|
|Breastplate/Robe||2 Dragon Discs||2 Elm Discs|
|Weapon||2 Dragon Discs||2 Crown Discs|