How do you deal with a friend who doesn't understand you are financially challenged?

I am a twenty something who is in my second round of college. I am nearing the end of my degree, and I am strapped for cash for the next few months until I get a job. One of my best friends doesn’t seem to get it. I get emails every other day about cheap travel deals, she invites me to expensive restaurants, and though I have politely declined certain things, she doesn’t seem to get the picture that even a $200—$300 trip is an expense I can’t do right now (isn’t everyone financially stretched these days?). How do I get it through her head without being a huge jerk? She is fixated on a trip with the rest of my friends, and they seem to get that I can’t go…and i’ve even said that they should all go and it wouldn’t hurt my feelings. I’m really sick of the emails!