I am going through an adoption now. And though my story is a little different since I am adopting from a cousin, I thought I'd provide some insight for you.
My cousin isn't getting a lawyer, as far as I know. The mother would need a lawyer if she wanted someone to review any paperwork she will be signing, like giving up parental rights, whether or not the adoptive parents are free to tell the child about her when they ask (since it's a known adoption this would be required).
I did require a home study, but found an agency that is working with me to expedite the process. This is usually the longest part of the process as I understand. Usually a 2-4 month process, my home study will be complete within a month of when I first dropped off my application. This total process, with all incidental fees to get fingerprinted and paperwork notarized, and to pay for 3 follow up visits after I bring my son home will be around $3219.
My lawyer fees, again including fingerprinting (I'm adopting in a different state then I live so I need to get fingerprinted and background checked in both states), and travel to state I'm adopting my son from will total around $2600.
The mother had medical insurance so I don't have any medical bills to cover. So adoption can be affordable, you just have to go the route that is best for you. It also doesn't have to be a lengthly process. From the time I found out about my son to the time I get to bring him home will be 2 months. That's barely enough time to get the house and my life prepared for an infant!