Services like GoDaddy, Google, 1&1, and BlueHost, to name a few allow you to buy your domain (and variations of it) for as cheap as $1/yr. We recommend securing your primary domain, its variations including .us, .org, .net, or other if available. If your domain is taken or is for sale for an outrageous amount, there are solutions available to you.
When purchasing your domain, your personal information is published in the WhoIs Public Internet Directory, which can be viewed by anyone. To keep your information secure, opt-in for private registration through your domain registrar. Doing so protects yourself from telemarketers, spammers, data miners, reduces the chance of identity theft, and shields your address from strangers.