Is this possible?
With the cameras that SDM and CHDK support ... no.
What are my options?
Very, very few.
The GoPro Hero2 may be suitable although I am not aware of synch being tested.
There are no plans for synch support with Hero3.
My understanding is the most accurate method is the SDM USB voltage method?
That is only for still images.
What setup/cameras would be ideal? (Trying to keep price 500-1000 range if possible)
What currency .. Zambian dollars ?
would prefer not to if the functionality already exists.
Inexpensive, synchronised movies using two separate cameras is an unsolved problem.
I am currently building a rig that synchs two keychain cameras to 1/5000 sec.
However, you probably want higher quality than that.