Sense for Business
2) Sarien says that even in the seemingly barren Wastelands there are valuable things to be found. When you accept his proposal to work together with him, he tells you to collect Monster Eye Carcasses for their magical meat, Monster Eye's Lenses and Basilisk's Gizzards, from which pieces of jade can be retrieved.
3) You can find Hungry Eyes (lvl 22, passive) just a few steps away from Sarien, right on the beach, and Wandering Eyes (lvl 21, passive) a bit further up the coast, at the Langk Lizardman Dwellings. Occasionally an aggressive Langk Lizardman Sentinel might molest you, but since they are lvl 19 they should be no problem. Apart from that those eyes can also be found in a strip of terrain between Windawood Manor and The Ruined Bend, but these are living together with aggressive lvl 23 Ol Mahum Deserters and poisonous Arachnid Predators, so I would not really recommend that.
Monster Eye Watchers (lvl 25, passive) and Monster Eye Destroyers (lvl 26, aggressive) are living along the rim of the Wastelands. Monster Eye Destroyers can also be found on the Plains of Dion.
For about every third kill you get a Monster Eye Carcass and at a rate of about 1 out of 50 a Monster Eye's Lens.
4) Lesser Basilisks (lvl 27, aggressive) and regular Basilisks (lvl 28, aggressive) are, like the Monster Eye Watchers and Destroyers, living along the rim of the Wastelands. You get a Basilisk's Gizzard for about every fifth or tenth kill.
5) When you made that contract with Sarien he told you to bring back as many items as possible. This would be unwise because, as so often, there is a bonus for 10 or more quest items. For 1 Monster Eye Carcass you get 25a, for 1 Monster Eye's Lens 1000a and for a Basilisk's Gizzard 60a. If you bring in 10 or more items, no matter which kind, there is a bonus of 618a. Here are some rewards I got:
The quest is infinitely repeatable.