While it may seem as if you can simply look at the amount of disk space offered and make a quick judgment, this is not an accurate assessment. Some hosting plans claim to offer unlimited disk space, yet cost a fraction of a plan that places a limit on the disk space. Which one is best?
In general, you don't want to compare unlimited plans with limited plans, simply because unlimited plans do not accurately depict your limitations. Simply put, unlimited hosting plans are actually quite limited in reality, especially when you read the fine print, but the vast majority of webmasters never reach those limits.
Anyways, be sure you are not purchasing an exuberant amount of disk space.