Max Elementalist armor is 60. There is no need for fancy or special armor types. The cheapest maxed armor you can find will work just fine. The Guild Wars Wiki displays the armor sets and tells you where to go in the game to buy them.
The armor headpiece you need is Earth Magic. This is important!

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Armor: Max level 60 Elementalist Armor with Earth Headpiece
There are multiple weapons you can utilize for this solo run. However make sure that the weapon has “Enchantments Last 20% Longer and Energy +5”. If you can get additional energy on your weapon then go for it, every little bit helps. A great suggestion for the weapon is a Totem Axe. Stats: Req 9 Axe Mastery, Armor penetration +20% chance 20%, Enchantments last 20% longer, and Energy +5.
Just like with the weapons your offhand can be anything you wish as long as it provides Energy +12 or higher. You can get an Earth Scroll in Droknar’s Forge for cheap. Stats: Req 9 Earth Magic, Energy +12, Armor +5 while enchanted, and Health +45 while enchanted.
Weapons: Totem Axe and Earth Scroll from Droknar’s Forge
Runes are what is going to cost you the most besides the armor set. It is very important to set your runes up in the following manner:
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- Head: Radiant Insignia, Elementalist Rune of Superior Earth Magic
- Chest: Survivor Insignia, Elementalist Rune of Major Energy Storage
- Gloves: Prismatic Insignia [Elementalist], Rune of Vitae
- Pants: Radiant Insignia, Rune of Superior Vigor
- Shoes: Geomancer Insignia [Elementalist], Rune of Vitae