Buy a Calculator
The first step in buying a calculator is identifying your needs. If your teacher has recommended a certain model of calculator, do your best to comply. After all, he or she probably has a lot more experience with calculators than you do. Not only that, your teacher may have a specific set of instructions for using a calculator in class, and it will be easier to help you if you have a calculator he or she is familiar with.
I have always been a fan of Texas Instruments' calculators, primarily because they are the most popular among students, ensuring compatibility with your classmates and teachers. These calculators can be purchased at most large electronics and office-supply stores, or you can buy one online from Amazon.com. In fact, you can help support FreeMathHelp.com by buying your calculators through our Amazon.com links below.
You have probably been told what type of calculator (scientific or graphing) that you will need. If you need a graphing calculator, skip this paragraph and keep reading. For scientific calculators, you basically have a number of products that all do the same functions, but some easier than others or with fancier displays. Right now I use the TI-30X for simple calculations at home, but of course it's a pretty powerful machine, great for Algebra 1 & 2. I like that this model has a two-line display which shows you what commands you have entered instead of just a number.
Graphing calculators are a little more difficult, and more expensive, to buy. A good calculator will probably cost you at least $100, but you may be able to rent, buy used, or even borrow from your school library. The TI-84+ is a good calculator for algebra and geometry (now available with a color screen), and is a newer version of the classic TI-83+. For about $135 you can buy a TI-89 Titaniumfrom Amazon.com (You might pay $199 to buy it from a store!) The 89 offers symbolic manipulation software to easily solve any equation automatically, and is a must for AP Calculus courses. I use the TI-89 all the time for more complicated math problems. It has far more power than the 84+/83+, and has a great interface. A more advanced calculator than that is the TI Nspire CX (allowed on most tests). I personally like and recommend the 89 for all serious math students, but if cost (or a teacher's rules) are prohibitive, go with an 84+.
You may be leaning towards a calculator from one of the other brands, like Casio or HP, and some of those are even more powerful than a TI-89. They're great machines, and if your teachers recommend them, then by all means, go for it. The fact is, though, that most American students use TI's in the classroom, and they are the easiest to use in my experience. And I'll say it again -- check with your teachers, even those you won't have for 2-3 years, before you or your parents plunk down $100 for a "cool looking" calculator that your teachers don't like!