Perfectly manicured raised beds built from prefab kits may look like a million dollars, but they don't increase the value of your vegetables. Save yourself some money, or better yet, put that money into seedlings and garden products that will actually improve your garden. There are plenty of inexpensive, or free, materials you can use to make a raised bed.
Recycled Lumber: Hit the junk pile for old pieces of wood or lumber left over from other construction projects. There is no standard size for a raised bed, other than keeping the width to 4 feet or less for easy access to plants. The University of Florida Extension explains that a bed with a width of 4 feet allows most gardeners to reach the center from both sides with ease. Cut the wood to the dimensions you desire and build a rough box. Place in a sunny location and fill with soil for a quick raised bed for growing vegetables. Remember to line the bottom with landscape fabric or canvas to create a weed barrier.
Wooden Crates: Scour the attic and storage shed for discarded wooden crates. Visit yard sales and flea markets to find an assortment of crates or wooden boxes. Use them as is by placing in a sunny location and filling with soil, or carefully remove the bottoms to expose to the soil underneath. Although crates and boxes may be a bit smaller than you envisioned, try combining several sizes and shapes to create a rustic display of raised beds brimming with fresh vegetables.