I can't fully agree with everything on WalkingOnSunshine's list.
oyster shell
grit
If you get oyster shell you don't need grit.
dewormer
Only if you have a worm problem. We never have.
hen house
Depends on the weather where you live. Here in Central Texas a little shelter that I made from scrap lumber is all they need.
run
Fencing, sure, but the run itself?
feeders
You can make your own.
wheel barrow
Already owned one, but use it infrequently for the chickens. Usually just a bucket is all we need.
shovel
ibid.
perches
Built some, but they don't use them much.
nest boxes
We use plastic milk crates on a frame built out of scrap lumber.
carton labels
Not required here, so it depends on the laws where you are. I did print up some business cards on card stock that we usually include it the cartons.
egg wash soap
Only if you wash your eggs. Our customers expect dirty eggs.
marketing materials, like sign at the end of the drive and what you spend registering your URL if you have a blog
Our sign I made out of scrap lumber. Did have to buy a couple of quarts of paint, and it's a onetime expense. We don't have a blog so...
Money spent to register as a business
Again, depends on the laws where you live. Here in Texas, as long as we just sell from our home we don't need one.
Of course, if you want to any expenses are tax deductible, but than you'll have to list the income as well. We operate under the theory that what the taxman doesn't know doesn't hurt him.
Our girls have been profitable for over 2 years now, and have even bailed us out a couple of times in cash emergencies.