As the Maid of Honor, what should I expect the other bridemaids to contribute?

I am throwing a bridal shower and bachlorette party in Vegas for my best friend. She has 7 bridesmaids and besides myself and her sister I do not really know the other girls. I know I am in charge of organizing and arranging these events but it has been super difficult 1)because I do not know these girls and 2) because they have been horrible about responding to my texts and emails. I booked our rooms for Vegas over a month ago, the place charged us half of the cost of the stay, it was immediately deducted from my account so I asked the girls to please pay me $50 (a little less than half of their portion). NO ONE has given me their $ yet and several have told me it was on it's way SEVERAL times. It is really getting old and I do not want to burden the bride with it. I also am dissappointed none are helping as far as the planning or prep of the shower go - or so much as asked. I have told them my ideas and said I would love any and all input and to please just let me know how they would like to contrubute. What should I do to get them more involved AND PAY ME (i have asked for the $ 3 times mind u). I think it is incredibly rude because I cannot imagine myself EVER not paying someone money I owed ASAP, especially a stranger. Just as much as I have responsibilities as a MOH I feel they have theirs as BMs. What to do?