It is a federal law that any turtle under 4 inches cannot be sold for any reason other than for educational use.
However a lot of states will allow them to be kept as pets. NJ being one of them.
As for salmonella, If the enclosure it is kept in is kept clean, and you clean your hands after handling it. there will be no problems. The problems in the 70's were mostly caused by the pet stores selling people the turtles in a little plastic dish with a plastic palm tree in the middle. (seriously dating myself here). They were then told they could change the water once a week. That caused a major buildup of waste which was then re ingested by the turtles, which allowed the salmonella bacteria to flourish.
Keep your tanks clean, and wash your hands (or use the purell hand sanitizer) after handling the little ones or their tanks, and you are very well protected against it.
In short if you care for your turtles properly, there is a very minute chance of ever contracting any salmonella at all. I have dealt with turtles since I was 5 (34 now). And have never had any ill effects. And when I was young I didn't practice good hygiene i.e. I would go out into the ponds near my home and catch and play with Res.'s and Snapping turtles, and painters and then after that sit down and eat my lunch without washing my hands.
If the law makers would sit down and analyze the hard facts they would find that more people get salmonella from handling chicken before cooking it than ever got from any reptile!
I hope this puts your mind at ease, and gives you enough info to explain to other people with the "turtles give you salmonella" mentality. Pass it on. Education is the key to loosening these ridiculous laws against herps that are being passed.