OK so im having MAJOR bridesmaid trouble!?

Ok so heres the deal, I have 5 brides maids. Ive already asked all 5 of them to be in the wedding and they are all very excited, ecspeically my maid of honor. Ok well, the dress that i have picked out has to be special ordered. Well since i can only special order it, that means all the brides maids have to pay up front by 2 marrow! if they are not paid up front by then, that means I do NOT get the dresses that i want. Ive told these girls in advance that they needed to be saving money so they can buy the dresses. They are not expensive dresses. So OF COURSE NONE of the girls have the money right now, so basically we cant get the dresses that i wanted them to wear. So now we have to find a dress that doesnt have to be special ordered. BUT..........here's where it gets complicated....................2 of my brides maids are prego. the special dresses that i picked out are also prego belly friendly. Me and the girls have looked EVERYWHERE for another dress that everyone can aford right now but none of the ones we like will fit the prego girls. And i still havent found one that i really liked. so ive told the girls that if they dont buy the dress that i wanted by 2 marrow then they arent in the wedding, im pretty much prepaired to just have no brides maids, now they are all SO UPSET! Half of them wont even talk to me! they are all so pissed off that i changed my mind and dont want any brides maids? what should i do? i dont wanna settle for a dress that i dont really like? it to much of a hle with all of this! am i being mean?