There are several internet sites that sell military surplus guns. I think that generally most of them are reputable, but I have heard of instances where what was shipped didn't exactly match what was advertised. I bought my first internet gun a few months ago, a Swiss K31. Looked at several sites while shopping, and eventually bought one from Gunbroker. I was very pleased with the transaction. I think that gunbroker is self policed and pretty safe. I just looked and they had 2 M96's for sale, one was very nice.
Another site that I liked, and trusted (I did call and talked to him on the phone) is Allan's Armory.
http://www.allans-armory.com/aa.php. Check out his description of M96's, it is probably very informative as you start shopping, especially if you want a 100% as-issued gun.
Only something like 850,000 M96's were made, and some of the rifles were cut down into carbines and many were sporterized. Good luck in your search as they are getting harder to find. But you'll be happy once you get one, they are great shooters!
Jim