I have a unique situation: I have rented my apartment from a friend for a few years now. They now want to sell the condo. When I floated the idea of buying it from them myself, they said they were open to it if that's what I wanted to do and gave me time to think about it. They aren't in a hurry and I've looked at similar units sold in this neighborhood and they're asking a very fair price. I like where I live and it has the potential to be a good rental for me down the line, so I've decided to go through with making the purchase. 

I'm a first time home buyer and was wondering how this situation would be different than a standard home sale. (I've read the First Time Home Buyers guide, so I have a good sense of the basic steps in the process!)

Do I need an agent? Does my friend need an agent? Neither of us want to pay expensive commissions if we don't need to. If an agent isn't necessary, is a lawyer or another type of representative a better choice? What else should I be considering in this case?