Activity for Katie

So my fiancé and I have decided to elope because of our own reasons. However we want to have a reception afterwards somewhere that isn't gonna break the bank. Can someone give me an idea of where to have a reception in or near king county?

I want to have my cousin be the one to officiate my wedding but I don't know how to have him become one for a non religious ceremony. My wedding is next June, can anyone help?