In my view, the two keys to eggplant success in home gardens are strong, early plant growth and protection from pesky flea beetles. If flea beetles find your plants AND the plants are weak, you will be buying local eggplant instead of growing local eggplant!
Here are some proven techniques for managing flea beetles and growing strong plants:
Jane Hayes is a Howard Co. Master Gardener who grows big eggplant crops each summer with her husband. They built a simple plastic-covered box with removable lid that encourages early growth and excludes flea beetles. They remove the frame when plants really start to take off- right before flowering. At that point flea beetles are not such a threat.
Howard Co. Master Gardener Linda Branagan runs the small demo garden at the Home and garden Information Center. She created a low tunnel using #9 wire hoops draped with a floating row cover. Here again, you get a double benefit of enhanced growth and no flea beetle access. The hoops are essential because eggplant foliage is sensitive and may burn if the fabric lays directly on plants.
Particle barriers can be applied to foliage to inhibit flea beetle feeding. These can be very effective but do require re-application after heavy rainfall. Below is a shot of leaves covered with wood ash. I shook some from a coffee can with holes punched in the bottom. I've tried this in past years with success. Below that photo is a plant sprayed with Surround, a commercial kaolin clay product that you mix with water. (Clean your sprayer parts after applying Surround to avoid clogs.) Yes, it looks weird- as if whitewashed, but the plants grow just fine. Here are links to more info on physical barriers:
http://www.hgic.umd.edu/content/whatsnew.cfm (click May/June 2010 newsletter)