One of my goals this summer was produce volumetric models for moai in order to determine center of mass and other physical parameters. Although $100K provides one the funds to purchase a 3D laser scanner, my approach was to do this using nothing more than a camera and photosynth. Using 100s of photos, www.photosynth.net, a point cloud extractor and some mesh editing software, this turned out to be laborious but possible. As a first step, I started with this photosynth of a statue that stands on a small ahu just a little ways from Tongariki.
You will need to install a VRML plugin on your machine (see: http://cic.nist.gov/vrml/vbdetect.html) or (much preferred - MeshLab for which there is a mac, linux and windows version). But when you do, check out:
I went from this (note that all the photos in the synth were taken in portrait mode and photosynth was unable to reconcile that fact with the landscape).