A lot would go by the interest and what people are willing to pay. Some people get $5-6/Dz. Some can't give eggs away. Its area and interest. With Just a few of each breed you would run risk of losing breeders or thinning blood to much. And selling breeding pairs/trios you have would be full siblings which can have some bad issues.
For live animals most people that are not really super interested in poultry (Like BYC crowd) wouldn't understand why they should pay more to you than hatchery or farms store for birds. With a decent size flock per breed you could potentially sell quite a few animals. But a lot of people won't take a free "mutt" chicken.
To start, a small flock of 5-10 of 1 breed would be best. 1 or 2 roos and rest hens. That way you get enough eggs to fill a incubator in a week or less. And if you only have 1 roo, he could have issues and be without a male for fertilization. Having enough hatch is another issue. People really don't care for breeders that tell them there will be plenty of birds at hatch and then get told, bad hatch were don't have any come back later (Happened to me recently, so wife told me no more trying to get from THAT breeder.) There are a million different ways things could go. Being NPIP tested would seriously increase your chances at success. Even then you could go into debt trying to make money.
Just remember not to count your chicks before they hatch. And make sure you follow all state/Federal laws. Or you could really be up a creek.