I hatched around 20 barnyard mix chicks in September. Put out a sign in front of the house that said CHICKS $2. They were all gone within 20 minutes. The chicks were mostly barred, some had naked necks which seemed to be something people really liked. I'm setting another 40 eggs tomorrow, focusing on naked necks and a few sex-links. Planning on selling them for 3 dollars this time.
I also posted on craigslist, but didn't get any interested buyers from there.
Hatching chicks can be risky, because unlike with fertilized eggs, you can't just stick them in the refrigerator if they don't sell. So you need a plan and enough room to raise them just in case. I slaughter cockerels and would sell more mature pullets.
Right now, only one feed store is selling chicks in my area, and they are going for $6 each. When they are out of season, you have way less competition. In spring, every feed store around is selling them including
Tractor Supply (and really cheap usually too).
My plan is to get some pure naked necks and breed those (hopefully quality, to the SOP). From there I am going to get my flock NPIP tested and will have the opportunity to ship if I choose.
Where you live is also a factor. Here in So Cal, some people post barnyard chicks for $7 or more. Pure breeds, especially silkies or polish can go for much more. In some areas even pure bred chicks may not go for more than 2 dollars, especially if they are straight run. Do some research into your local market and see what most people are posting them for, then go a little lower.
Good luck in your venture!