There are a few websites out there that will send an e-mail to him explaining his problem or a sample size deodorant, soaps and such for a small fee, so he'll take the hint without you and your floormates having to confront him directly.
http://sendatip.com/ - Has a wide assortment of negative (and positive) traits that you can send an anonymous e-mail to bring to their attention.
http://getevennow.com/revenge/revengebodyodor.asp - For $9.50 (you should be able to raise that easily if that many people have a problem with this guy) you can have the "body odor kit" of a bar of soap, stick of deodorant, and box of Gas-X sent to him.
Good luck!
-Mikey