I was selling 2yr old red stars for $10 (cuz I'm getting into breeding and don't need them) and I had everyone and their brother calling for them.  I start day old mutts at $2 each in the spring.  Early spring I sell POL pullets for $15 (mutts) $20 (pet quality purebreds- If I had show quality I could get much much more but I don't show so I'm still learning what to look for).  $45 for a broody australorp and a couple of her mutt chicks (proven broodiness/mothering is a HUGE underated market in the country).  Had someone stop in to see if I had any POL pullets for sale (I don't) and tried talking me into selling her some of my POL cuckoo marans to her for $4 each!!!!!!!!!!!!!!!!!!!!! She said they were going for $2 at the auction (I told her to go back and get some but explained that they were cockerels).   
That being said I'm picking up an EE hen and her 3- 1month old chicks today and am getting them for a steal for $20 (gotta love yardsales).  The lady only wants $10 but I am giving her $20 cuz I REALLY REALLY REALLY want more of her birds if she ever decides to get rid of a few more.   Gorgeous birds and all are freeranged super healthy.  
Honestly, if I was in your shoes I'd give them 4 chickens cuz they are nice enough to watch your DDIL's chickens so that you could spend time with your kids and grandbabies (I'm assuming your a grandma from the "nana" in your name).    This is assuming that they didn't charge your DDIL to watch the chickens.   Or if you want to make a little money back, charge like $5 each.  This is pretty much what we would do in the hills of PA.