Before you jump in, you may want to check ordinances where you live. There may be limits on the number you can keep via the city or county, and its best to know before you get started as it helps with planning. As others have said - minimum of 3 (they are social creatures and are unhappy kept alone. Two runs you the risk that if you lose one, you still have a lone chook. So 3 is the minimum I would consider to allow for the loss of one). Two per family member is a good equation. In my family I find we eat a lot more on weekends than during the week. With kids heading off to school starting at 7am, I don't have time to cook breakfast in the morning so all they get is a bowl of cereal. I might go all week without cracking a single egg. Then on weekends, I get up and make French Toast and go through a bunch all at once. You will use more when they are freely available than when you have to buy them. For example, if I make pancakes from scratch, I'll use 3-4 eggs because they're there, although only 2 would really be needed. I also boil up a dozen at a time to put in the fridge for snacks, or add a fried egg to sandwiches that wouldn't need it if I had to buy it.
As for where to get them, your timing is excellent. Chick Days are starting all over the country and they will be available at most feed stores and even some garden supply stores.