user registration

hi guys! i have a unique problem here. I use wordpress as a cms for my clothing site, which i plan to finish and launch soon. i have a section dedicated for the retailers carrying my clothing lines. I want to create a login/registration page for just retailers only. once they have registered and logged in, they can order my products on a page dedicated for just retailers. any ideas, suggestions, plugins on how i go about doing this? any help is appreciated. thanks a lot!