Unless you have a very big site the Basic Hosting package is probably all you need.
Start there and let's see how you go. We won't suspend your account if you hit your quota as long as you upgrade immediately - we'll charge on a pro-rata basis.
Basic hosting includes a single website. You can then add additional websites for a low annual fee - you only pay for what you actually need.
Have a look at the 123host competitive hosting prices via the hosting link in the top menu.