Who Pays And How Much?

I am the Maid of Honor in my sister`s wedding and I am currently planning her bridal shower. I have found the place, favors, centerpieces, etc for the shower. However before I bought or booked anything I asked the other brides maid how much they are willing to spend. Many of them said that they are suppose to pay about 100 dollars and the rest falls on my mom and the grooms mother. For the shower I wanted to plan, I would need more than hundred dollars per bridesmaid. My mother does not work and cannot afford more than she has offered. Is it tacky to ask the mother of the groom to contribute more, can I ask for more than hundred dollars per bridesmaid, or should I replan the whole shower so that the bridesmaid wont have to pay that much? I want my sister`s shower to be perfect. Thank you for any type of help you can give me.