Hen night dress ideas?

My brother is getting married this year and i'd like to arrange accesories for all hens/perhaps a cosume for the bride to be. We're going on a low key outdoorsy weekend but will be doing a couple of pubs in the evening. Nothing too slutty or vulgar (though a little bit vulgar is ok ;) . Does anyone have any ideas of what could work? Links to websites would be great. Relatively low budget so no �50 costumes for all. Perhaps just a little something, hats etc. for the hens.