Depends ,who and where. I paid 1 for week olds. I charge $2.00 for adults for dog trainers. I would expect to pay anywhere from $1.00 to $3.00 each. But you may luck out if you have a poultry auction nearby, some of those go cheap.
I will have adults in 8 more weeks but none now. I check the site daily and if I have any later I could sell you a few.
I know those thoughts well it took me 6 weeks or so to build mine. My flight pen is 12 x 32 x 6 and it's 1 to 2 foot off the ground. the cost was about $400.00 to build.
Here's a few pictures of it. Although there is only 40 quail in it now I hope to house several hundred in it.
When you say a "small flock", what numbers are you looking at? I have between 110 and 125 and consider that a small flock. When I sell adults I get $3 each and normally sell 3 hens and 1 roo as a breeding group. Mine are kept in all wire cages, 2 ft. x 3 ft., and I keep 12 birds to a cage.
I'm in the process of moving and will probably move my birds within the next week. I'll likely thin down to around 100 so could help you out. 9 hens and 3 roos should do fine in 2' x 3' pen. I feed 22% protein layer pellets and 12 birds will go through about 1 quart a day.
One word of warning, I started with a dozen. Now one freezer shelf full of quail, about a dozen pints of pickled eggs, around 400 eggs in the fridge, untold amount of eggs (guessing 600 to 700) given to a friend, and if I weren't moving I'd be building pens and incubating eggs. Chickens aren't additive, QUAIL ARE!!!!