hi...I don't really know much about fermenting veggies, other people on here are more knowledgable. but I think the idea with air locks is it allows an anarobic environment but allows the gasses to escape. a vacuum system is too closed I think.
since, I've discovered something I think will work for doing this. there are places that sell rubber lids that fit various jar sizes (wide mouth too) with a hole in them already to fit air locks. so if you have the jars already, the lids are available and very inexpensive. it looked like it would work for mason jars, but I haven't had the time to get them or try it out.