Canon cameras are uniquely suitable and cost effective for such a task and I'll explain why.
I believe Canon released some information regarding their firmware which has resulted in a couple of custom firmware projects for Canon cameras.
Most notable would be the "Canon Hack Development Kit" (CHDK) http://chdk.wikia.com/wiki/CHDK
It will add some very advanced and unique features to many inexpensive point-and-shoot Canon cameras, giving them advanced functionality that often surpasses that in the best Professional cameras. (This includes the ability to set batch scripting functions, which no other camera has, of which I am aware)
Additionally, it also allows you to use the camera's USB port to build an inexpensive device to synchronize any number of cameras together so they are able to synchronize shots.
You could build a rig above the subject, affix an array of relatively inexpensive cameras to it, and synch the cameras to go off at the exact same time using the USB cable synchronization.
If it is not critical that the photos be taken at exactly the same moment, being synchronized with USB cables, you could use CHDK's scripting feature to take a "time lapse" photo, by telling the cameras to start taking photos every set interval starting at a certain time. So you can synchronize all camera's clocks, script it to start at a certain hour, and they will all start taking photos every X minutes/hours at roughly the same time for as long as you have specified. Of course you may want to provide an external power adapter for the cameras for long term usage and for consistent performance across all cameras.
Read up on CHDK in the link provided and it's features and you may be surprised with all you can do, and find additional applications.
Alternatively, you could setup a rig using one camera, in a fixed spot above the subject and take overlapping, multiple photos, and stitch them together as a panorama, then simply do some perspective correction. This would be the most cost-effective solution because it would only involve one camera in a fixed position, throughout the entire process.
In either case, you may need to "stitch" photos together. Hugin is an opensource and free program that is capable of a multitude of image processing techniques. Photo-stitching being one of it's main feature focus. You can find it here and read more in depth about it: http://hugin.sourceforge.net/
There is more to CHDK and Hugin than can be covered here, but they are both very powerful and if used effectively, I believe will be able to help you accomplish your goal.
Hope this helps!