Reno's Envirohaven Corp. so far has been a feel-good story collegiate business plan brings about the creation of a real-life company but the company now faces a real-life challenge:Generating a sale.Not a bunch of sales, but a single sale to show the world how its pre-packaged, self-sufficient homes can meet the need for housing in remote areas ranging from mining camps to tribal reservations.It's a challenge for a little company that's progressed so far on a share of the $35,000 in prizes that Envirohaven won this spring in the annual Donald W. Reynolds Governor's Cup, a collegiate business plan competition.Vicki …