am I super fucked up for this?

My childhood friend asked me to be a bridesmaid in her wedding and Informed us that we're going to vegas for her bachelorette party . The flight alone will be 325 plus I have to take a day off of work and the activities they chose for us to do while we're there will cost 175.00 that does. It include pitching in for her part of everything or food and alcohol . I honestly just can't afford it I live on my own in my only income and I think I have to tell her it's just not feasible for me to spend 700 plus for a weekend in vegas . Is that so wrong of me I'm feeling terrible but it's just a lot to ask of someone