They look really yummy! Hobby Lobby/Micheals have really cute cupcake paper and decorations you can stick in them. I'm not sure if those stores are in your area, but any craft store should have awesome cupcake stuff. I don't have any good recipes, my cupcakes come out of a box, lol.
Did you already make the invites?
I made my own save the dates, RSVPs, and invites all for about $40 (and I made about 150 of each), here is what my invite looks like.
And if you guys are needing dresses, this site has really great prices. I know it's an international company, but most prom dresses come from China anyhow. One of my bridesmaids got her last bridesmaid dress from this company and was happy with it. www.tbdress.com there are a TON of wedding dresses on that site for next to nothing. I'm sure the dress will come in a box and need steamed though. I ordered my bridesmaid dresses from the site and I'm waiting for them to come in, so I can't vogue for how nice the dresses are or aren't.