Your cost is not in the land, in this case, but rather in the improvements necessary to make development feasible. A very interesting alternative, and possibility for otherwise "unbuildable" sites can be found with a very specific, earthquake, hillside friendly building method that I have worked with recently. There is a site:
http://www.haikuhouses.com that offers pole construction buildings. These are very Japanese inspired in nature, and can be constructed on otherwise unbuildable sites.
When it comes to land - grab your geo-engineer, and prepare to pay for some r & d if you're thinking about shopping in the lower price range for the Hollywood Hills.
What a great question. After you do the ground work (foundation, grading and retaining) and the cost of the land a good price is $250 per square foot for basic builder's grade finishes. For an exact amount you will need to speak with a contractor to review the properties requirements. Building a home in the Hollywood Hills is a great investment but it can be costly so check the project and if you can get land with permits that is ready to build all the better. Also keep in mind that financing is difficult for land right now. Cash is king.
The Carrabba Group
Keller Williams Hollywood Hills
Hope this helped!
Coldwell Banker/ The Bremner Group
33 Years Residential Realtor
"Your Home Is Waiting"