Buying a Haggadah
JewFAQ.org says, if you want to know more about Pesach, the best place to start is with the Haggadah. It is the book used at the table and is read backwards (back to front) as are other books written in Hebrew. The Haggadah was written as a teaching tool to allow people at all levels to learn the significance of Pesach and its symbols.

There are a wide variety of Haggadahs available for every political and religious point of view: traditional haggadahs, liberal haggadahs, mystical haggadahs, feminist haggadahs, and others.

If you're buying a haggadah for study or collection, there are many with extensive commentary or with pictures from illuminated medieval haggadahs.

However, if you're buying Haggadahs for actual use at a seder, you're best off with an inexpensive paperback. Keep in mind that you'll need one for everybody, you're likely to get food and wine on these things, and you'll be using them year after year. You can even find them in some grocery aisles.