Invasive prenatal testing?

I am trying to find out literally as soon as possible the father of my child. It is between 2 guys. I have no way to tell unless I get this done because I had sex with them 1 day apart. Does anybody know anything about it? How much it cost and when I can get it done? I'm 7 weeks. Tomorrow will be 8. I live in Pennsylvania. I did some research on my own and some places are over $900 and $1,000 which is a lot. I was hoping to find somewhere cheaper. Not knowing who the father is stresses me out soooo much.