If you're willing to buy exotic armor with karma, then indeed, the Mortal armor of Grenth sold in Temple of Grenth seems a good option. If you're looking for runes which cause condition damage, you can check them here.
Another interesting dungeon armors with different attributes you could take a look:
- Flame Legion armor
Condition Damage + Power + Vitality (+315 / +224 / +224 Attributes)
- Sorrow's Embrace armor
Power + Vitality + Condition Damage (+315 / +224 / +224 Attributes)
- Corrupted armor
Precision + Toughness + Condition Damage (+224 / +224 / +315 Attributes)
- Nightmare armor
Condition Damage + Toughness + Precision (+315 / +224 / +224 Attributes)
Precision + Power + Condition Damage (+315 / +224 / +224 Attributes)
- Inquest armor
Power + Precision + Condition Damage ( +224 / +315 / +214 Attributes )
Power + Condition Damage + Magic Find (+224 / +224 / +18%)
- Noble's armor
- 3 combinations with
Condition damage as a 224 atribute
- Honor of the Waves armor
Precision + Toughness + Condition Damage (+315 / +224 / +224 Attributes)
- Corrupted armor
Precision + Toughness + Condition Damage (+224 / +224 / +315 Attributes)
You may also would like to take a look in Ogden's armor and Khilbron's armor
Resuming: There are several sets which contain condition damage, you may choose one that fits more your play style.