DDOS Mitigation

As a soon-to-be small business owner (web-based) one thing that's been on my mind lately is the potential for DDOS attacks to take down my site, lose me customers, and cost me business. I've found a number of different services that claim to provide DDOS protection but can't seem to figure out which one is the right one for me. I'm planning on deploying on EC2 and have found a product there called aiProtect. It seems to be an hourly service I can sign up for when under attack, or permanently with my instance for pre-emptive protection (a very costly approach). In digging around I've also found different providers such as Prolexic, Arbor Networks, Cloud Flare, and now even apparently Google is getting into the game. My question to you is: how do you protect your Amazon EC2 instances from DDOS attacks? Does aiProtect do everything I need? I suppose this could benefit more people if it were a general discussion of DDOS mitigation techniques and providers, so I'm fine with that too.