My girlfriend developed a significant deer problem this summer, with two young bucks and a doe that decided that her garden was actually theirs, and were eating pretty much everything, in exchange for their generous gift of e-coli on what they didn't eat or trample. As urban deer, these young punks weren't even remotely afraid of her, and wouldn't move even if she made menacing gestures while shouting. She was getting ready to break the law and make venison steaks out of them, she was so frustrated.
Because the home is a rental, and we're always on a limited budget with even greater time constraints, she didn't want to invest a lot of time and money into a huge fencing project. I did a little research, and found what I was looking for.
I wound up picking up a motion-activated sprinkler. It's just like a motion sensor for a light, but it activates a sprinkler, so it's a creative solution. It is activated by a nine-volt battery, which is supposed to last for 4 months. The manufacturer suggests keeping the sensitivity down so that the sprinkler isn't going off when the deer at at a longer distance.
By keeping the unit set to a lower sensitivity, the deer are close enough to be both surprised, and hit with a jet of sprinkler water when the unit is triggered. They go airborne, sideways... They really don't seem to enjoy the unit as much as we do
I picked our sprinkler up for $50 at a local hardware store - it is called a scarecrow. We haven't lost so much as another leaf out of the garden to large grazers, and it keeps out Mr. Kitty from next door, who until recently, thought that a vegetable garden was also a litter box. No more poop, no more grazing, just beautiful, yummy veggies.