Looking to buy my wife a vacuum sealer for Christmas, but I have zero experience with these and don't know what to look for. I want a decent unit even if it costs some coin, one that will last. I keep seeing online bags and rolls of plastic for sealer use--- do certain ones use rolls versus bags? What is the most economical way to get replacement bags/rolls, I see they can get pretty pricey. If anyone has any recommendations on one they've used or know about, or any info on the subject, I'd appreciate it.