i would agree that the most important accessory for a reader is books.
be sure to take a look at the free books available on this site ("e-books" link in the blue bar at the top of the page ; for kindle, get mobipocket format) as well as other sites like feedbooks.com, munseys, etc.
i don't know what conditions you like to read in but i always read with ambiant light from a lamp so i don't need a special booklight ; i think that in general, if you have enough light to read a paper book, you have enough light to read a kindle. i know that a lot of people need booklights so they can read without disturbing other people by keeping the light on. i think you're right, wait until you have it, and see how you like it. you might not need a booklight at all.