While it's tempting to set up a sprinkler to cover a lot of ground (and enjoy that summertime smell in the air, not to mention listen to the ch-ch-ch-chhhhhh sound we so love), sprinklers are best for lawns—not raised vegetable beds.
According to this article at the Mother Nature Network, the most efficient way to water vegetable and flower beds is by a slow and steady drip method. This requires a little more work on the front end (setting up a hose system in each bed will take time and money) but the up-keep is as simple as turning on the water when it's time.
Vegetables and flowering plants respond best to deep soaks at their bases, which encourage roots to reach deeper into the ground for water. Sprinkling, on the other hand, encourages shallow root growth—and wastes water in areas that don't need it.