I went and looked at mine... it's the Foodsaver Vac1050. It has two buttons, "On" and "Manual Seal". It will continue to run (vacuum) until one of two things occur... 1. Max vacuum is achieved, at which time the sealer function is applied, or 2. manual seal is pressed.
I use manual seal to make bags, as I'm sure everyone else does, but I can also use it when I see juices being sucked towards the sealer to immediately stop the vacuum action and seal the bag. Works great! Actually, I've found that even when the sealer sucks up a bit of juice, I still usually get a good seal.
This model gets great reviews, and from what I can tell by just doing a quick Google search it sells for $120 - $180 depending on attachment options. Yes, bags are a little pricey, but with proper care some can be reused and even fresh bags probably cost less than throwing away all that food, and there is really no better way to keep food.
Ok, I've tried several times to post a pic of this thing, but it doesn't seem to be working today. If you are interested you'll have to click the link.