What sort of show is this? A consumer, home kinda thing, a local association show? What works in that atmosphere is the same kind of thing that has always worked when trying to gather the masses for a pitch, from the snake oil salesman of yore to todays hottub peddler. Got to give them something to look at, something to ask questions about. Tough for lawn apps and irrigation although you can get some large photographic displays and such if you thought far enough in advance and have the $$$. Low budget? Get a cute girl(s), find or make a roulette(think wheel of fortune) wheel, put some prizes on it, including say a year's service or a irrigation design, throw in some t's or hats with your logo on them, stickers and buy some boxes of candybars at the local sams or costco. People enter in a form for a spin, giving you the opportunity to make a list to market at a later time and presto bango, you hold them for long enough to make an impression, develop some leads and maybe even answer a few q's to those a little more serious. You've got to get a chance with the "roamers" so don't be afraid to "carny" it up a bit. That's the nature of successful campaigns for those types of things.