I have been working on a small game and I wanted to load it onto my iPhone to see how well it will run. Do i still have to buy the 99 dollar dev account even though I don't have any plans of releasing it on the app store."?
Yes. Getting the App on your iPhone is no simple task. You need to pay for a developer account, and then use the Apple Provisioning Portal to create the needed certificates that will let you deploy the app to your iPhone. You'll get access to all the documentation you need once you are an approved developer.
Further more, you will need the iPhone version of Unity. Can't remember whether this costs or not, but you have all that info on www.unity3d.com