I've been thinking about making up some Obama magnetic signs for my car but I've yet to get up the guts to put my bumper sticker on the car. (Republican in the house!!)
Buildasign.com has good prices and an easy to use interface for designing your own sign. Since we develop .net web applications where I work, I am always impressed to see creative sites built in asp.net. Since you do your own designing, you save on the cost of a designer so your end cost is much lower. I'm going to tell my friend about the real estate signs. It would be fun to make a couple of prank ones for his yard. I am remembering the time my mom and I stuck an "I love horses" bumper sticker on my dad's truck. My dad hated my horses and one had just bit him on the wrist and broke his watch. He was not amused.