Congratulations, and welcome to Mage Wars! It remains my favourite board game after nearly six months now, which is a personal lifetime record for me. ; )
No, it is most definitely *not* correct that a spellbook without at least two teleports will not be able to compete. Teleport isn't good enough by itself to make that claim valid. However. Not including two teleports is (almost) always a sub-optimal decision, and many players argue that not including three is sub-optimal. (I'm not one of the three minimum crowd though.)
Let me try an analogy: if you play a (Straywood) Beastmaster, you almost always want a lot of animals in your book. Since you're putting a lot of animals in your book, you are almost always going to want to include a Ring of Beasts. Will you automatically lose most games if you don't include that Ring? No, of course not. But the ring is so good in that combination, that you need to have a very good reason *not* to include it in your spellbook.
Teleport is like that, but with every spellbook; if you don't include at least two, you need to have a good reason not to. Here are two good reasons for you to use: 1) I don't have enough copies of the spell to use, and I don't like constantly switching out cards from other books. 2) My local meta is different from most other ones, in that they don't play enough cards that would make Teleport truly useful enough to justify the 8-spellbook-point cost (for everyone but Wizard) of including two of them.
Go ahead and create books with only one (or even 0!) Teleport, it's not going to break your game. If you ever *can* though, try to include at least two. Teleport really is useful enough to justify that, in most books.
Without having read further up the thread for this, I will perhaps be going against the stream of comments. I do not think you have to have any teleports in your book. It really depends on what you are trying to accomplish with your chosen mage whether to include any. Is teleport a useful spell - sure it is. Is it required to have one, or more - no it is not. I would go further and say that while you can get away without them depending on your local players styles, it still holds that beyond your local group you can also skip them. You do need to be wary of things like strangle vine, and plan accordingly. But teleport is a utility spell, and has random applicability. You also need to be aware your opponent could be playing it, and might play one on you or himself etc.
I expect I will get jumped on for the above. I believe I am a decent player, and I rarely include teleport in any of my books - including my tournement viable builds. My local play groups includes some very strong players.
So be aware there are varied opinions on this, and you just need to form your own.