So there's this con coming up in the town I'm living in about a month away.
My friend and I are really excited about this, since this is one of our favorite cons (we've going there for the last two years). She wants to do a Tokyo Ghoul cosplay with her as Tsukiyama and me as Rize (think of the ending song of the first season; the part showing Rize and Tsukiyama surrounded by red flowers). I'm excited like her, but here's a problem.

I'm not exactly sure if I want to cosplay.

Don't get me wrong! I love cosplaying and cosplayers. The two previous years of cosplaying are with easy characters, like Izaya and Sherlock. However, this year is going to be a pretty big project. The problem is that I don't have the budget for it. My friend tells me to just save up and buy only the necessities, when I can't even get those. My dad is currently unemployed, and my mom is working at a nail salon. We aren't exactly rich people. I only own two pairs of shoes, four pairs of jeans, and enough graphic tees to last me for a year. I keep telling her this, but I don't think she really understands the situation. I look for materials and clothing similar to Rize, but they are so expensive. And counting that I am no sewing/crafty guru.
Another problem is that I can't see myself in that cosplay; as in I don't see myself as Rize. I know that cosplay is about having fun and not caring about what others think of you, but there's always that part of insecurity where I can't help but think "I don't look like Rize; I'm not skinny enough, tall enough, pale enough, pretty enough, etc." I know this is horrible to think, but I can't help but think of that every time I am in a cosplay.
I don't know if I should tell my friend about this and just not cosplay or something else....
What should I do?

i understand how you feel. There alot of people even me who feel like this sometimes. About you being afraid to tell you friend i think its best to tell her. If she is a true friend she will understand.