Doula?

Kelly
For those of you using a doula how did you find her and how did you pick the right one? How much (roughly) should I expect to spend? I'm in northern NJ. 
If you didn't go the doula route who did you have in the room with you? 
I'm trying to decide if my husband and I would appreciate the help or if it would not be that helpful given the cost. I don't want our mothers and I don't have a sister. My closest friend lives too far away to be there. 
TIA!