Hi,
I never found a 'freebie' database that had all of the VIN numbers.
I talked with people at GM and got some information that allows for decoding a fair percentage of their automobiles. It is not comprehensive and you would need many of the 'fact' sheets to compile all of GM's line. Plus, Ford, Dodge etc employ different ways to get the information.
Depending upon the level of information you want to supply your client
http://www.vinlink.com/ is one of the better solutions that I have found that's even better than dataone.
I seriously considered, and would entertain the notion if I had mucho dinero and if I also had more time than I knew what to do with, creating a VIN decoding system.
It's really a massive undertaking and when you compare what it would take to do all domestic vehicles you would have significant R&D effort. It would take years to complete and years to recoup the expenses.
Some of these people have been working on their systems for 20+ years and the amount of data they have acquired is beyond staggering.
For simplicity sake, best to find a good decode company, bite the bullet and pay them. Reduces headaches and stress
Hope this helps.
wiz