I'm not convinced that researching the Friendly AI concept is a cost-effective way of reducing existential risk.

Researching Friendly AI is a way to reduce the risk of Unfriendly AI.

Personally, I find it very easy to outline a recipe for FAI.

1. You use cognitive neuroscience to figure out human values and human metaethical thought.

2. You automate human metaethical thought, apply that to the values determined at step 1, and thereby arrive at a human-relative moral/behavioral ideal.

3. You design an open-ended AGI architecture, and use the ideal from step 2 to supply it with a goal.

To me, that defines a research program that's just full of highly concrete tasks waiting to be carried out. Some of them may be very difficult or abstract, but nothing leaves me feeling helpless, with no idea where to begin. However, you need to know something about ordinary AI (try this), and you need to have some idea of what a computational model of human decision making might look like (simple examples).