Fleets of mobile homes are expected to flood the campgrounds in Waukesha County, Wisc., this spring, marking the beginning of the camping season there. Mobile units are quickly becoming the toy of choice for retirees and baby boomers who have had the good fortune to retire early. Waukesha County is currently the second largest motor home community in the area, with 1,164 registered motor homes, according to state Department of Motor Vehicle records. Motor homes can cost anywhere from $48,000 to $300,000 for deluxe models. Fifth-wheel models, which are designed to be towed by pickups, begin in the $12,000 range and can go as high as $97,000. Folding campers and travel trailers are the most popular ticket items among campers because they are not as expensive as motor homes and are more flexible than pickup campers.