Personally, I like the idea. Part of me thinks that if there wasn't a fee for the classes, more people would choose to take them. Some people, myself included, have to save a while just to make a gun purchase, the extra cost of a class (which can be expensive) can be daunting to a new gun owner.
However, the realistic side of me says that we would still end up paying for the class in the long run. Gun manufacturers are not going to want to pay for it. Unfortunately, I'm sure they would eventually add the cost of the voucher to the handgun price. Although if that is what it takes to make firearm ownership safer. Maybe it would be worth the small price increase.