Can you use your own bags for this or do you need proprietary bags?
You can use your own bags. They come with two rolls of the bags that you can home-make with the food saver, but you could just as easily use the mylar bags that potato chips usually come in. Or you could cut the top off of ziplock bags and use those.
the one The Wilderness bought for us is awesome. We've used it to save marshmallows, reseal chip bags, save a couple of dinners, store dried raviolini in (it also comes with a couple of canisters, and the hose to suck out all the air), and I've put home made bread in a couple of bags and sealed them in without crushing them (that takes a little practice, though

).
I whole-heartedly recommend these puppies to anybody and everybody!