I have one like this: FoodSaver V2840 Advanced Design Vacuum Food Sealer
I use bags now and then, for meat etc.. I have found the weston brand to be the cheapest.
Weston 30-0101-W 8-by-12-Inch Vacuum-Sealer Food Bags, 100 Count
I've not had any failures and I'm half way through my first box.
BUT - if you have canning jars like I do, then the foodsaver jar sealer is the answer, its under $10 and is used in conjunction with your sealing machine, using the tubing that comes with the machine.
FoodSaver T03-0023-01 Wide-Mouth Jar Sealer
You can re-use it tons of times, you don't waste bags by cutting them open and making them too small to re-seal etc.. you can vacuum seal anything you can put into the jar! I love it.
You do need to wiggle a spoon at the rim to get it open after its been sealed, it makes it a little ticky to open - but you'll add months of life to your food.
Some people make a tiny hole in their lids, seal that hole with some tape (electrical) then seal the jar, when they need to open the jar, they remove the tape to release the suction on the lid, the tape can be put back or a new piece used and resealed again.
All in all - the jar sealer saves money!