I've seen a couple of goldwing conversions that are really nice, but you need the bike, and then you have to buy the kit and have it built. Expensive proposition. 20 for the bike and another 10 for the kit. Another thought would be to throw a side car on it. Here's a couple links you can check into. Sorry I couldn't be more help.
http://www.dfttrikes.com/index2.htm http://www.inb.net/hannigan/index.html http://www.libertysidecars.com/ http://www.championsidecars.com/