Bridal Shower Question

I am one of 2 brides maids in a wedding for my best friend who is getting married off the coast of california. Both parties getting married are not from afluent backgrounds so they are funding the wedding themselves. Since I have to pay for my own expenses to the wedding totaling 2,000 dollars, should she expect both brides maids to throw her a shower and finance it also? Oh! I have to purchase my dress as well.
She indicated that it is proper ediquette for the brides maids to throw her the shower as a gift? She wants to invite 36 people. She doesn`t want anything to do with the shower because it should be the bridesmaids gift to her.