She’s higher 20’s and my other sister and bro in law are going. I’m 19.

I’m pretty poor, and they are going to a place that is 15-20$ a plate.

The issue here is 1. I can’t afford it 2. Saturday night is my only night off and they told me about it this morning, i need to plan ahead for things like this because I was planning on just staying home and 3. I don’t wanna go 

AITA if I don’t go? 