Another option is an ultrasonic leak detector. I was able to find on on the Internet for just over $100. The nice thing about them is they come with a transmitter that you can place on the inside of your coach and then go outside with the leak detector and figure out where you're getting wind noises and air leaks. Here's a link to a 5 page post about tracking down air leaks
http://www.luxurycoachlifestyle.com/...ly-system.html