Hello!
My name is Magen and I live in New Berlin, SE Wisconsin. My husband and I are currently looking into starting a small flock of buff orpington, as I've read that they are very good with small children (we have an 11 year old, 10 year old, and 8 year old) and docile.
I don't have any yet, but will be visiting our local feed store tomorrow to check out availability and cost. I know it's a lot to ship live animals, so I don't want to go the route of a hatchery yet.
Any advice on a good coop for around $300 for 4-5 hens would be appreciated, along with any other advice you have for a beginner!
Nice to meet everyone!

That is a very wise decision not to go the route of shipping chicks from a hatchery to start out. That can be very hard on the chicks and losses are to be expected.
Before we can give you much coop advice, we will need a bit more info to help you out. Does New Berlin have size restrictions for coops? About how large of a space do you have to dedicate to your chicken coop & run? As most of us on here will attest, we usually recommend going with the largest coop you can get away with, as chickens are very addicting and chicken math is inevitable.

If you have close neighbors, I highly recommend a sturdy run for your girls which should also be as large as it can be. Chickens love to kill grass & any vegetation they can get their little claws on (and your neighbors might not appreciate that very much). If anyone owns a dog, you will want to keep your girls safe from them and other predators too.
Here are a few links you might want to peruse before you decide to get chickens. As our very wise Bigzio said, it is always a very good idea to research getting an animal before you actually get the animal so you know exactly what to expect before it happens. There are very many things to consider. And after doing your research, you might decide that chickens aren't the best fit for you for one reason or another. It is much easier to come to that decision before you have the birds.
Chicken 101:
http://www.motherearthnews.com/homesteading-and-livestock/are-you-ready-for-chickens-chickens-101.aspx
Basic chick care:
The My Pet Chicken Guide to Chicken Care, Chapter 4: Caring for baby chicks
The My Pet Chicken Guide to Chicken Care, Chapter 4: Caring for baby chicks
Chapter 4 of the chicken care e-book: Raising and caring for day old baby chicks.
View on www.mypetchicken.com
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Backyard Chicken Basics

Backyard Chicken Basics
Backyard chickens come in countless varieties. Keeping chickens will teach you basic livestock handling, and these hardy birds will amaze you with their individual ...
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Links to darn near anything poultry:
Poultry Sites

Poultry Sites
poultry links
View on www.feathersite.com
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Good luck! And feel free to ask more questions. We will try our best to help.