We are going to be blunt about this one because the category usually is not. A vacuum sealer is not a preservation method. It removes oxygen, which suppresses the moulds and spoilage bacteria that would otherwise warn you something has gone wrong, and does nothing at all to the organism that grows without oxygen. Read the vacuum-packing page before you buy one.
What it is genuinely good for: keeping dry goods dry, compressing bulky things like pasta and oats into a shape that packs, and portioning. What it is not good for is making anything moist last longer outside a fridge.
If you want it for the first list, it earns its money. If you want it for the second, it will not do what you are hoping.