Whenever I shell out $500 or more for anything, I tend to think it over quite a while. The iPad 2 is no exception. I thought simply deciding to hit the “Buy Now” button at the Apple online store was the big decision. I was wrong. It turns out, it was just the first of many decisions. We all like to think that Apple is just offering two tablets — the old iPad and new iPad 2 — but really, Apple is offering no fewer than 18 possible combinations of iPad 2 features, depending on storage, color, and possible 3G cellular service carrier.