The USDA's National Center for Home Food Preservation has a good primer on
freezing foods - from general info to the best methods for specific foods.
Vacuum Sealers: yes, these do require special bags. No, they are not in the $25 or less catagory - and even the cheaper ones are going to be expensive ($75 or so). And, the bags are not all that cheap. They are great for long term (2-3 years) storage of some things, especially meats, but not absolutely necessary for produce.
Zip-Lock Bags: Get the freezer bags - they are much less porous than the regular ones which are only intended for short term storage in the refrigerator. I use these all the time for liquid items (soups, stews, chili, tomato sauces, etc.) - I just put the item into the bag, seal it leaving just a small 1/2-inch or so unclosed, squeeze out all the air I can without out expressing any liquid, and then finish sealing it. I then lay them flat in the freezer until frozen - and then I can stack or stand them up any way I want. I know this method works for 1-2 years storage.
Ice Blocks: Some things, like fruits in syrup or vegetables in water, can be frozen in cubes/blocks and then wrapped in vaporproof wrappings. This was basically the method used when frozen foods first hit the market - but only good to 6-12 months storage. They were blanched, frozen, packaged in waxed paper boxes, and then wrapped in waxed paper wrappers.
Like GB and Andy M. said - the biggest contributors to freezer burn are "frost-free" freezers, porous packaging, and air. The greatest lost of color, nutrition and texture in produce is the failure blanch before freezing.