Wow! I am stunned that anyone is suggesting more than $25 for a First Communion! This is not a wedding - though we don't usually give more than $50 for a wedding unless we are very close to the couple. I realize small town, midwest is very different from Connecticut, but I am still stunned!
My husband and I were both raised Catholic, and I used to work for the Church. First Communions are a very big deal to Catholics and their families, but that's usually about it. Maybe some close friends, but it's not like a Wedding at all. There's usually a brunch or something at the house afterwards, but not a big reception at a hotel or anything.
If I'm totally off base here and there really is a big shindig, maybe $25 is more appropriate. For friends birthdays we usually do around $25, so I was really thinking $10 for a First Communion.